Spatial clustering and meteorological drivers of summer ozone in Europe

NASA Astrophysics Data System (ADS)

Carro-Calvo, Leopoldo; Ordóñez, Carlos; García-Herrera, Ricardo; Schnell, Jordan L.

2017-10-01

We have applied the k-means clustering technique on a maximum daily 8-h running average near-surface ozone (MDA8 O3) gridded dataset over Europe at 1° × 1° resolution for summer 1998-2012. This has resulted in a spatial division of nine regions where ozone presents coherent spatiotemporal patterns. The role of meteorology in the variability of ozone at different time scales has been investigated by using daily meteorological fields from the NCEP-NCAR meteorological reanalysis. In the five regions of central-southern Europe ozone extremes (exceedances of the summer 95th percentile) occur mostly under anticyclonic circulation or weak sea level pressure gradients which trigger elevated temperatures and the recirculation of air masses. In the four northern regions extremes are associated with high-latitude anticyclones that divert the typical westerly flow at those latitudes and cause the advection of aged air masses from the south. The impact of meteorology on the day-to-day variability of ozone has been assessed by means of two different types of multiple linear models. These include as predictors meteorological fields averaged within the regions (;region-based; approach) or synoptic indices indicating the degree of resemblance between the daily meteorological fields over a large domain (25°-70° N, 35° W - 35° E) and their corresponding composites for extreme ozone days (;index-based; approach). With the first approach, a reduced set of variables, always including daily maximum temperature within the region, explains 47-66% of the variability (adjusted R2) in central-southern Europe, while more complex models are needed to explain 27-49% of the variability in the northern regions. The index-based approach yields better results for the regions of northern Europe, with adjusted R2 = 40-57%. Finally, both methodologies have also been applied to reproduce the interannual variability of ozone, with the best models explaining 66-88% of the variance in central-southern Europe and 45-66% in the north. Thus, the regionalisation carried out in this work has allowed establishing clear distinctions between the meteorological drivers of ozone in northern Europe and in the rest of the continent. These drivers are consistent across the different time scales examined (extremes, day-to-day and interannual), which gives confidence in the robustness of the results.

The Southern Hemisphere Additional Ozonesondes (SHADOZ) 1998-2002 Tropical Ozone Climatology. 3; Instrumentation and Station-to-Station Variability

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacqueline C.; Smit, Herman G. J.; Oltmans, Samuel J.; Johnson, Bryan J.; Kirchhoff, Volker W. J. H.; Schmidlin, Francis J.

2004-01-01

Abstract: Since 1998 the Southern Hemisphere ADditional OZonesondes (SHADOZ) project has collected more than 2000 ozone profiles from a dozen tropical and subtropical sites using balloon-borne electrochemical concentration cell (ECC) ozonesondes. The data (with accompanying pressure-temperature-humidity soundings) are archived. Analysis of ozonesonde imprecision within the SHADOZ dataset revealed that variations in ozonesonde technique could lead to station-to-station biases in the measurements. In this paper imprecisions and accuracy in the SHADOZ dataset are examined in light of new data. When SHADOZ total ozone column amounts are compared to version 8 TOMS (2004 release), discrepancies between sonde and satellite datasets decline 1-2 percentage points on average, compared to version 7 TOMS. Variability among stations is evaluated using total ozone normalized to TOMS and results of laboratory tests on ozonesondes (JOSE-2O00, Julich Ozonesonde Intercomparison Experiment). Ozone deviations from a standard instrument in the JOSE flight simulation chamber resemble those of SHADOZ station data relative to a SHADOZ-defined climatological reference. Certain systematic variations in SHADOZ ozone profiles are accounted for by differences in solution composition, data processing and instrument (manufacturer). Instrument bias leads to a greater ozone measurement above 25 km over Nairobi and to lower total column ozone at three Pacific sites compared to other SHADOZ stations at 0-20 deg.S.

Evolution of the Antarctic polar vortex in spring: Response of a GCM to a prescribed Antarctic ozone hole

NASA Technical Reports Server (NTRS)

Boville, B. A.; Kiehl, J. T.; Briegleb, B. P.

1988-01-01

The possible effect of the Antartic ozone hole on the evolution of the polar vortex during late winter and spring using a general circulation model (GCM) is examined. The GCM is a version of the NCAR Community Climate Model whose domain extends from the surface to the mesosphere and is similar to that described on Boville and Randel (1986). Ozone is not a predicted variable in the model. A zonally averaged ozone distribution is specified as a function of latitude, pressure and month for the radiation parameterization. Rather that explicitly address reasons for the formation of the ozone hole, researchers postulate its existence and ask what effect it has on the subsequent evolution of the vortex. The evolution of the model when an ozone hole is imposed is then discussed.

Uncertainties in Episodic Ozone Modeling Stemming from Uncertainties in the Meteorological Fields.

NASA Astrophysics Data System (ADS)

Biswas, Jhumoor; Trivikrama Rao, S.

2001-02-01

This paper examines the uncertainty associated with photochemical modeling using the Variable-Grid Urban Airshed Model (UAM-V) with two different prognostic meteorological models. The meteorological fields for ozone episodes that occurred during 17-20 June, 12-15 July, and 30 July-2 August in the summer of 1995 were derived from two meteorological models, the Regional Atmospheric Modeling System (RAMS) and the Fifth-Generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5). The simulated ozone concentrations from the two photochemical modeling systems, namely, RAMS/UAM-V and MM5/UAM-V, are compared with each other and with ozone observations from several monitoring sites in the eastern United States. The overall results indicate that neither modeling system performs significantly better than the other in reproducing the observed ozone concentrations. The results reveal that there is a significant variability, about 20% at the 95% level of confidence, in the modeled 1-h ozone concentration maxima from one modeling system to the other for a given episode. The model-to-model variability in the simulated ozone levels is for most part attributable to the unsystematic type of errors. The directionality for emission controls (i.e., NOx versus VOC sensitivity) is also evaluated with UAM-V using hypothetical emission reductions. The results reveal that not only the improvement in ozone but also the VOC-sensitive and NOx-sensitive regimes are influenced by the differences in the meteorological fields. Both modeling systems indicate that a large portion of the eastern United States is NOx limited, but there are model-to-model and episode-to-episode differences at individual grid cells regarding the efficacy of emission reductions.

The Global Structure of UTLS Ozone in GEOS-5: A Multi-Year Assimilation of EOS Aura Data

NASA Technical Reports Server (NTRS)

Wargan, Krzysztof; Pawson, Steven; Olsen, Mark A.; Witte, Jacquelyn C.; Douglass, Anne R.; Ziemke, Jerald R.; Strahan, Susan E.; Nielsen, J. Eric

2015-01-01

Eight years of ozone measurements retrieved from the Ozone Monitoring Instrument (OMI) and the Microwave Limb Sounder, both on the EOS Aura satellite, have been assimilated into the Goddard Earth Observing System version 5 (GEOS-5) data assimilation system. This study thoroughly evaluates this assimilated product, highlighting its potential for science. The impact of observations on the GEOS-5 system is explored by examining the spatial distribution of the observation-minus-forecast statistics. Independent data are used for product validation. The correlation coefficient of the lower-stratospheric ozone column with ozonesondes is 0.99 and the bias is 0.5%, indicating the success of the assimilation in reproducing the ozone variability in that layer. The upper-tropospheric assimilated ozone column is about 10% lower than the ozonesonde column but the correlation is still high (0.87). The assimilation is shown to realistically capture the sharp cross-tropopause gradient in ozone mixing ratio. Occurrence of transport-driven low ozone laminae in the assimilation system is similar to that obtained from the High Resolution Dynamics Limb Sounder (HIRDLS) above the 400 K potential temperature surface but the assimilation produces fewer laminae than seen by HIRDLS below that surface. Although the assimilation produces 5 - 8 fewer occurrences per day (up to approximately 20%) during the three years of HIRDLS data, the interannual variability is captured correctly. This data-driven assimilated product is complementary to ozone fields generated from chemistry and transport models. Applications include study of the radiative forcing by ozone and tracer transport near the tropopause.

Impacts of ozone-vegetation coupling and feedbacks on global air quality, ecosystems and food security

NASA Astrophysics Data System (ADS)

Tai, A. P. K.

2016-12-01

Surface ozone is an air pollutant of significant concerns due to its harmful effects on human health, vegetation and crop productivity. Chronic ozone exposure is shown to reduce photosynthesis and interfere with gas exchange in plants, thereby influencing surface energy balance and biogeochemical fluxes with important ramifications for climate and atmospheric composition, including possible feedbacks onto ozone itself that are not well understood. Ozone damage on crops has been well documented, but a mechanistic understanding is not well established. Here we present several results pertaining to the effects of ozone-vegetation coupling on air quality, ecosystems and agriculture. Using the Community Earth System Model (CESM), we find that inclusion of ozone damage on plants reduces the global land carbon sink by up to 5%, while simulated ozone is enhanced by up to 6 ppbv North America, Europe and East Asia. This strong positive feedback on ozone air quality via ozone-vegetation coupling arises mainly from reduced stomatal conductance, which induces two feedback pathways: 1) reduced dry deposition and ozone uptake; and 2) reduced evapotranspiration that enhances vegetation temperature and thus isoprene emission. Using the same ozone-vegetation scheme in a crop model within CESM, we further examine the impacts of historical ozone exposure on global crop production. We contrast our model results with a separate statistical analysis designed to characterize the spatial variability of crop-ozone-temperature relationships and account for the confounding effect of ozone-temperature covariation, using multidecadal global datasets of crop yields, agroclimatic variables and ozone exposures. We find that several crops (especially C4 crops such as maize) exhibit stronger sensitivities to ozone than found by field studies or in CESM simulations. We also find a strong anticorrelation between crop sensitivities and average ozone levels, reflecting biological adaptive ozone resistance that is not accounted for in current generation of crop models. Our results show that a more complete understanding of ozone-vegetation interactions is necessary to derive more realistic future projections of climate, air quality, ecosystem functions and food security.

CHARACTERIZATION OF EMISSIONS FROM A VARIABLE GASOLINE/METHANOL FUELED CAR

EPA Science Inventory

In response to the occurrence of the increasingly severe ambient ozone exceedances, regional environmental managers are examining the possibility of a cleaner fuel for automobiles. t this time the leading candidate is methanol. n anticipation of a shift to methanol, variable-fuel...

Variability and changes in tropospheric ozone over the western United States (1980-2010): Exploring the roles of stratosphere-to-troposphere transport and El Niño-Southern Oscillation

NASA Astrophysics Data System (ADS)

Lin, M.; Fiore, A. M.; Horowitz, L. W.; Naik, V.; Oltmans, S. J.; Levy, H.; Cooper, O. R.; Johnson, B. J.

2011-12-01

Understanding the drivers of inter-annual variability and long-term changes of tropospheric ozone is crucial for designing appropriate control policies. Advancing this knowledge will also enable process-oriented assessments of chemistry-climate models, which are needed to build confidence in their utility for projecting tropospheric ozone under future climate scenarios. We examine here the response of North American background ozone over the past 30 years (1980-2010) to changes in atmospheric circulation and chemistry, both in the stratosphere and in the troposphere, through an integrated analysis of observational records from satellite, ozonesonde and ground-based networks with the GFDL AM3 global chemistry-climate model (nudged to reanalysis winds to allow for exact space-time comparisons with the observational datasets). Comparing the model simulation with ~30 years of ozone measurements at Mauna Loa ground station (~3397 m a.s.l.) and Hilo sonde (550-450 hPa) in Hawaii, we find that mid-tropospheric ozone in the eastern Pacific extratropics is enhanced by ~5-10 ppbv (~10-20% deviations from the climatological mean) during strong El Niño events (i.e. 1982-1983, 1997-1998, 2009-2010), presumably reflecting stronger transport from the stratosphere and Asia due to the eastward extension of the Pacific storm tracks and amplified subtropical jet. The La Niña condition typically manifests in the opposite sign, with ozone decreasing north of Hawaii. Over the western U.S., however, both cyclonic and anticyclonic circulation following strong El Niño and La Niña winters, respectively, may enhance deep stratosphere-to-troposphere transport in spring. Both ozonesonde and model results sampled at Trinidad Head, California, indicate ~25% positive deviations in UT/LS ozone during the El Niño winters of 1997-1998 and 2009-2010. We find that this ENSO-related UT/LS ozone variability is also captured in satellite-derived total column ozone from TOMS and AIRS over the Northwest U.S. in May. In contrast, enhanced lower tropospheric ozone over the western U.S. during strong La Niña years (e.g. 1999) mostly reflect changes in atmospheric dynamics rather than lower stratospheric ozone. The model indicates a 0.2 ppb/yr increase in mid-tropospheric ozone over the past 25 years. We are implementing a stratospheric ozone tracer in the model to quantify the springtime stratospheric enhancement to the high tail of daily maximum 8-hour surface ozone frequency during both phases of ENSO. We expect that the associated variability should provide insights regarding potential responses to climate shifts as well as inform air quality planning and control strategies to attain the national standard.

Spatial regression analysis on 32 years of total column ozone data

NASA Astrophysics Data System (ADS)

Knibbe, J. S.; van der A, R. J.; de Laat, A. T. J.

2014-08-01

Multiple-regression analyses have been performed on 32 years of total ozone column data that was spatially gridded with a 1 × 1.5° resolution. The total ozone data consist of the MSR (Multi Sensor Reanalysis; 1979-2008) and 2 years of assimilated SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) ozone data (2009-2010). The two-dimensionality in this data set allows us to perform the regressions locally and investigate spatial patterns of regression coefficients and their explanatory power. Seasonal dependencies of ozone on regressors are included in the analysis. A new physically oriented model is developed to parameterize stratospheric ozone. Ozone variations on nonseasonal timescales are parameterized by explanatory variables describing the solar cycle, stratospheric aerosols, the quasi-biennial oscillation (QBO), El Niño-Southern Oscillation (ENSO) and stratospheric alternative halogens which are parameterized by the effective equivalent stratospheric chlorine (EESC). For several explanatory variables, seasonally adjusted versions of these explanatory variables are constructed to account for the difference in their effect on ozone throughout the year. To account for seasonal variation in ozone, explanatory variables describing the polar vortex, geopotential height, potential vorticity and average day length are included. Results of this regression model are compared to that of a similar analysis based on a more commonly applied statistically oriented model. The physically oriented model provides spatial patterns in the regression results for each explanatory variable. The EESC has a significant depleting effect on ozone at mid- and high latitudes, the solar cycle affects ozone positively mostly in the Southern Hemisphere, stratospheric aerosols affect ozone negatively at high northern latitudes, the effect of QBO is positive and negative in the tropics and mid- to high latitudes, respectively, and ENSO affects ozone negatively between 30° N and 30° S, particularly over the Pacific. The contribution of explanatory variables describing seasonal ozone variation is generally large at mid- to high latitudes. We observe ozone increases with potential vorticity and day length and ozone decreases with geopotential height and variable ozone effects due to the polar vortex in regions to the north and south of the polar vortices. Recovery of ozone is identified globally. However, recovery rates and uncertainties strongly depend on choices that can be made in defining the explanatory variables. The application of several trend models, each with their own pros and cons, yields a large range of recovery rate estimates. Overall these results suggest that care has to be taken in determining ozone recovery rates, in particular for the Antarctic ozone hole.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reiter, R.; Kanter, H. J.; Sladkovic, R.

The balance of the tropospheric ozone is studied with regard to sources and sinks. The influx of stratospheric ozone through stratospheric intrusions and photochemical production under pure air conditions is discussed. The 4-year measuring series (1977-1980) of the ozone concentration measured at 3 different levels are evaluated, the influence of meteorological parameters is examined. The time variation of the ozone layer between 1000 and 3000 m ASL is investigated as a function of different ozone sources. First results show that stratospheric ozone arriving at the troposphere penetrates only in a few rare cases to the ground layer below 1500 mmore » ASL. Most of the time, the variation of ozone concentration in this layer is determined by photochemical processes which are, in turn, controlled by meteorological parameters. The upper boundary of the photochemically active layer is found at about 500 m above ground. Variability of the concentration of stratospheric aerosol and its optical properties after the volcanic eruptions in the year 1980 are discussed on the basis on lidar backscattering measurements.« less

Causes of Interannual Variability over the Southern Hemispheric Tropospheric Ozone Maximum

NASA Technical Reports Server (NTRS)

Liu, Junhua; Rodriguez, Jose M.; Steenrod, Stephen D.; Douglass, Anne R.; Logan, Jennifer A.; Olsen, Mark A.; Wargan, Krzysztog; Ziemke, Jerald R.

2017-01-01

We examine the relative contribution of processes controlling the interannual variability (IAV) of tropospheric ozone over four sub-regions of the southern hemispheric tropospheric ozone maximum (SHTOM) over a 20-year period. Our study is based on hindcast simulations from the National Aeronautics and Space Administration Global Modeling Initiative chemistry transport model (NASA GMI-CTM) of tropospheric and stratospheric chemistry, driven by assimilated Modern Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Our analysis shows that over SHTOM region, the IAV of the stratospheric contribution is the most important factor driving the IAV of upper tropospheric ozone (270 hectopascals), where ozone has a strong radiative effect. Over the South Atlantic region, the contribution from surface emissions to the IAV of ozone exceeds that from stratospheric input at and below 430 hectopascals. Over the South Indian Ocean, the IAV of stratospheric ozone makes the largest contribution to the IAV of ozone with little or no influence from surface emissions at 270 and 430 hectopascals in austral winter. Over the tropical South Atlantic region, the contribution from IAV of stratospheric input dominates in austral winter at 270 hectopascals and drops to less than half but is still significant at 430 hectopascals. Emission contributions are not significant at these two levels. The IAV of lightning over this region also contributes to the IAV of ozone in September and December. Over the tropical southeastern Pacific, the contribution of the IAV of stratospheric input is significant at 270 and 430 hectopascals in austral winter, and emissions have little influence.

Causes of interannual variability over the southern hemispheric tropospheric ozone maximum

NASA Astrophysics Data System (ADS)

Liu, Junhua; Rodriguez, Jose M.; Steenrod, Stephen D.; Douglass, Anne R.; Logan, Jennifer A.; Olsen, Mark A.; Wargan, Krzysztof; Ziemke, Jerald R.

2017-03-01

We examine the relative contribution of processes controlling the interannual variability (IAV) of tropospheric ozone over four sub-regions of the southern hemispheric tropospheric ozone maximum (SHTOM) over a 20-year period. Our study is based on hindcast simulations from the National Aeronautics and Space Administration Global Modeling Initiative chemistry transport model (NASA GMI-CTM) of tropospheric and stratospheric chemistry, driven by assimilated Modern Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Our analysis shows that over SHTOM region, the IAV of the stratospheric contribution is the most important factor driving the IAV of upper tropospheric ozone (270 hPa), where ozone has a strong radiative effect. Over the South Atlantic region, the contribution from surface emissions to the IAV of ozone exceeds that from stratospheric input at and below 430 hPa. Over the South Indian Ocean, the IAV of stratospheric ozone makes the largest contribution to the IAV of ozone with little or no influence from surface emissions at 270 and 430 hPa in austral winter. Over the tropical South Atlantic region, the contribution from IAV of stratospheric input dominates in austral winter at 270 hPa and drops to less than half but is still significant at 430 hPa. Emission contributions are not significant at these two levels. The IAV of lightning over this region also contributes to the IAV of ozone in September and December. Over the tropical southeastern Pacific, the contribution of the IAV of stratospheric input is significant at 270 and 430 hPa in austral winter, and emissions have little influence.

Observed ozone exceedances in Italy: statistical analysis and modelling in the period 2002-2015

NASA Astrophysics Data System (ADS)

Falasca, Serena; Curci, Gabriele; Candeloro, Luca; Conte, Annamaria; Ippoliti, Carla

2017-04-01

Local ambient air quality is strongly influenced by anthropogenic emissions and meteorological conditions. The year 2015 is considered by NASA scientists as one of the hottest at the global scale since 1880. Furthermore, in Europe it was the first summer after the introduction of Euro6 regulation, the latest emission standard for passenger vehicles. The goal of this study is twofold: (1) the investigation of the impact of the heat wave occurred in the summer of 2015 on ozone levels and (2) the exploration of the weight of temperature as driver of high-level ozone events with respect to other variables. We performed a quantitative examination of the ozone seasons (May-September) for the period 2002-2015 using ozone concentration and weather data from 24 stations across Italy. The number of exceedances of limit values set by the European directive was calculated for each year, and compared with the trend of ozone concentration and temperature. Furthermore, the data were grouped in clusters of consecutive days of ozone exceedances in order to characterize the duration and the intensity of high ozone events. Finally, we developed a multivariate logistic regression model to investigate the role of a set of independent variables (meteorological, and temporal variables, altitude, number of inhabitants, vehicle emission standard) on the probability of exceedances. Results show that 2015 is one of the hottest years after 2003. During the period 2002-2015, the average number of exceedances per station of the daily maximum 8-hour average is often higher than the limit established by the European directive (25 per year). The highest number of exceedances was 65 per station, reached in 2003. The Po Valley is confirmed as a hot spot for pollution, with more frequent exceedances and a higher sensitivity to temperature, especially at urban sites. Ozone events in 2015 were fewer than recent years, but of longer duration (on average 4 days against 3 days), and with similar mean concentrations. On the other hand, high-temperature events have similar duration and higher mean temperature with respect to recent years, pointing out that temperature is not the only driver of high-ozone events. The statistical model confirms a significant impact of the meteorological variables (positive for temperature and pressure, negative for humidity and wind speed) on the probability of ozone events. Significant predictors are also the altitude (negative) and the number of inhabitants (positive). The decreasing observed recent trend is explained by the introduction of the Euro regulations, rather than natural variability. However, we find an inversion of trend for the more recent period under Euro6 (from September 2014), but we cautionary wait a confirmation from additional data at least for the year 2016.

Atmospheric Ozone Response to the Disrupted 2015-2016 Quasi-Biennial Oscillation

NASA Technical Reports Server (NTRS)

Kramarova, N. A.; Tweedy, O. V.; Strahan, S. E.; Newman, P. A.; Coy, L.; Randel, W. J.; Park, M.; Waugh, D. W.; Frith, S.

2017-01-01

The quasi-biennial oscillation (QBO) - a quasi-periodic alternation between easterly and westerly zonal winds in the tropical stratosphere - is a main driver of inter-annual ozone variability in the stratosphere. During the late-2015 through 2016 time period, the QBO experienced a major disruption unlike any observed since wind measurements began in 1953. We examined the ozone response to this QBO disruption using profile ozone measurements from the Aura Microwave Limb Sounder (MLS) and Ozone Mapping and Profiler Suite Limb Profiler and total column measurements from the Solar Backscatter Ultraviolet (SBUV) Merged Ozone Data Set (MOD). Positive anomalies in stratospheric equatorial O3 developed between 50 and 30 hPa in May-September of 2016, and negative ozone anomalies were observed in the subtropics of both hemispheres. As a consequence of this QBO disruption, extratropical total ozone values during the spring-summer 2016 were at or near seasonal record lows over the more than 40 years of the total ozone record, resulting in an increase of surface UV index during northern hemisphere summer. We found very consistent responses in all considered ozone observations in terms of time, amplitude and spatial patterns. We will show the ozone changes associated with this disrupted QBO throughout the winter and spring 2017.

The Nevada Rural Ozone Initiative: Field measurements of surface ozone in rural settings

NASA Astrophysics Data System (ADS)

Fine, R.; Gustin, M. S.; Weiss-Penzias, P. S.; Jaffe, D. A.; Peterson, C.

2011-12-01

The Nevada Rural Ozone Initiative (NVROI) focuses on measuring ozone and other parameters at rural sites across Nevada. The project was prompted by observations of elevated ozone concentrations at Great Basin National Park (GBNP), a remote location at the eastern boundary of the state. Past CASTNET data collected at GBNP demonstrated that the area will be out of attainment if the new ozone NAAQS are established at any values between 60 and 70 ppb. To examine the ozone sources we have augmented the CASTNET data at GBNP with measurements at additional sites. NVROI field sites are situated between 1390 and 2080 meters above sea level along transects consistent with the prevailing wind directions across the state. Data collection began in July 2011. Measurements indicate significant variability in the diel pattern of ozone concentrations between field sites suggesting that site specific physicochemical characteristics, free tropospheric inputs, and regional transport of air pollutants all influence observed values at these background sites. Ancillary gas, particulate matter, and meteorological parameters will be coupled with trajectory analyses to investigate the influence of local, regional, and long range sources on background ozone concentrations.

Interannual variability in tropical tropospheric ozone and OH: The role of lightning

NASA Astrophysics Data System (ADS)

Murray, Lee T.; Logan, Jennifer A.; Jacob, Daniel J.

2013-10-01

Nitrogen oxide radicals (NOx) produced by lightning are natural precursors for the production of the dominant tropospheric oxidants, OH and ozone. Observations of the interannual variability (IAV) of tropical ozone and of global mean OH (from the methyl chloroform proxy) offer a window for understanding the sensitivity of ozone and OH to environmental factors. We present the results of simulations for 1998-2006 using the GEOS-Chem chemical transport model (CTM) with IAV in tropical lightning constrained by satellite observations from the Lightning Imaging Sensor. We find that this imposed IAV in lightning NOx improves the ability of the model to reproduce observed IAV in tropical ozone and OH. Lightning is far more important than biomass burning in driving the IAV of tropical ozone, even though the IAV of NOx emissions from fires is greater than that from lightning. Our results indicate that the IAV in tropospheric OH is highly sensitive to lightning relative to other emissions and suggest that lightning contributes an important fraction of the observed IAV in OH inferred from the methyl chloroform proxy. Lightning affects OH through the HO2+ NO reaction, an effect compounded by positive feedback from the resulting increase in ozone production and in CO loss. We can account in the model for the observed increase in OH in 1998-2004 and for its IAV, but the model fails to explain the OH decrease in 2004-2006. We find that stratospheric ozone plays little role in driving IAV in OH during 1998-2006, in contrast to previous studies that examined earlier periods.

Stratosphere-to-Troposphere Transport Revealed by Ground-based Lidar and Ozonesonde at a Midlatitude Site

NASA Technical Reports Server (NTRS)

Kuang, Shi; Newchurch, M. J.; Burris, John; Wang, Lihua; Knupp, Kevin; Huang, Guanyu

2013-01-01

This paper presents ozone structures measured by a ground-based ozone lidar and ozonesonde at Huntsville, Alabama, on 27-29 April 2010 originating from a stratosphere-to-troposphere transport event associated with a cutoff cyclone and tropopause fold. In this case, the tropopause reached 6 km and the stratospheric intrusion resulted in a 2-km thick elevated ozone layer with values between 70 and 85 ppbv descending from the 306-K to 298-K isentropic surface at a rate of 5 km day1. The potential temperature was provided by a collocated microwave profiling radiometer. We examine the corresponding meteorological fields and potential vorticity (PV) structures derived from the analysis data from the North American Mesoscale model. The 2-PVU (PV unit) surface, defined as the dynamic tropopause, is able to capture the variations of the ozone tropopause estimated from the ozonesonde and lidar measurements. The estimated ozone/PV ratio, from the measured ozone and model derived PV, for the mixing layer between the troposphere and stratosphere is approximately 41 ppbv/PVU with an uncertainty of approximately 33%. Within two days, the estimated mass of ozone irreversibly transported from the stratospheric into the troposphere is between 0.07 Tg (0.9 10(exp33) molecules) and 0.11 Tg (1.3 10(exp33) molecules) with an estimated uncertainty of 59%. Tropospheric ozone exhibited enormous variability due to the complicated mixing processes. Low ozone and large variability were observed in the mid-troposphere after the stratospheric intrusion due to the westerly advection including the transition from a cyclonic system to an anticyclonic system. This study using high temporal and vertical-resolution measurements suggests that, in this case, stratospheric air quickly lost its stratospheric characteristics once it is irreversibly mixed down into the troposphere.

Correlative nature of ozone and carbon monoxide in the troposphere - Implications for the tropospheric ozone budget

NASA Technical Reports Server (NTRS)

Fishman, J.; Seiler, W.

1983-01-01

The small-scale vertical variability of troposheric O3 and CO is examined using a set of simultaneous measurements obtained in July and August 1974 between 55 deg S and 67 deg N. From this set of vertical profiles, it is found that many of the fluctuations are coincident in both species, and a method is presented that quantifies the correlation between the observed O3 and CO variability. A two-dimensional depiction of the distribution of these O3-CO correlations reveals that there are regions in the troposphere where these trace gases are positively correlated and that, at the same time, there are preferred locations where these two species are primarily anticorrelated. The regions of anticorrelation are found to be consistent with the traditional picture of the tropospheric ozone cycle, suggesting that this gas is chemically unreactive in the troposphere. On the other hand, the location and magnitude of the region in which these two species are positively correlated indicates that there is considerable in situ production of tropospheric ozone.

On the origin of regional spring time ozone episodes in the Western Mediterranean

NASA Astrophysics Data System (ADS)

Kalabokas, Pavlos; Hjorth, Jens; Foret, Gilles; Dufour, Gaëlle; Eremenko, Maxim; Siour, Guillaume; Cuesta, Juan; Beekmann, Matthias

2017-04-01

For the identification of regional spring time ozone episodes, rural EMEP ozone measurements from countries surrounding the Western Mediterranean (Spain, France, Switzerland, Italy, Malta) have been examined with emphasis on periods of high ozone, according to the daily variation of the afternoon (12:00 - 18:00) ozone. For two selected high ozone episodes in April-May 2008, composite NCEP/NCAR reanalysis maps of various meteorological parameters and/or their anomalies (geopotential height, specific humidity, vertical velocity omega, vector wind speed and temperature) at various tropospheric pressure levels have been examined together with the corresponding satellite IASI ozone measurements (at 3 and 10 km), CHIMERE simulations, vertical ozone soundings and HYSPLIT back trajectories (Kalabokas et al., 2016). The results show that high surface ozone is measured at several countries simultaneously over several days. Also, the examined spring ozone episodes in Western Mediterranean and Central Europe are linked to synoptic meteorological conditions very similar to those recently observed in summertime ozone episodes over the Eastern Mediterranean (Doche et al., 2014; Kalabokas et al., 2015 and references therein), where the transport of tropospheric ozone-rich air masses through atmospheric subsidence influences significantly the boundary layer and surface ozone concentrations. In particular, the geographic areas with observed tropospheric subsidence seem to be the transition regions between high pressure and low pressure systems. IASI satellite measurements show extended areas of high tropospheric ozone over the low pressure systems adjacent to the anticyclones, which influence significantly the boundary layer and surface ozone concentrations within the anticyclones by subsidence and advection, in addition to the photochemically produced ozone there, resulting to exceedances of the 60 ppb standard for human health protection over extended geographical areas. References Doche, C., Dufour, G., Foret, G., Eremenko, M., Cuesta, J., Beekmann, M., and Kalabokas, P., 2014. Summertime tropospheric-ozone variability over the Mediterranean basin observed with IASI, Atmos. Chem. Phys., 14, 10589-10600. Kalabokas P. D., Thouret V., Cammas J.-P., Volz-Τhomas A., Boulanger D., Repapis C.C., 2015. The geographical distribution of meteorological parameters associated with high and low summer ozone levels in the lower troposphere and the boundary layer over the eastern Mediterranean (Cairo case), Tellus B, 67, 27853, http://dx.doi.org/10.3402/tellusb.v67.27853. Kalabokas P., J. Hjorth, G. Foret, G. Dufour, M. Eremenko, G. Siour, J. Cuesta, M. Beekmann, 2016. An investigation on the origin of regional spring time ozone episodes in the Western Mediterranean and Central Europe. Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-615.

Ozone trends over the United States at different times of day

NASA Astrophysics Data System (ADS)

Yan, Yingying; Lin, Jintai; He, Cenlin

2018-01-01

In the United States, the decline of summertime daytime peak ozone in the last 20 years has been clearly connected to reductions in anthropogenic emissions. However, questions remain about how and through what mechanisms ozone at other times of day have changed over recent decades. Here we analyze the interannual variability and trends of ozone at different hours of day, using observations from about 1000 US sites during 1990-2014. We find a clear diurnal cycle both in the magnitude of ozone trends and in the relative importance of climate variability versus anthropogenic emissions to ozone changes. Interannual climate variability has mainly been associated with the detrended fluctuation in the US annual daytime ozone over 1990-2014, with a much smaller effect on the nighttime ozone. Reductions in anthropogenic emissions of nitrogen oxides have led to substantial growth in the US annual average nighttime ozone due to reduced ozone titration, while the summertime daytime ozone has declined. Environmental policymaking might consider further improvements to reduce ozone levels at night and other non-peak hours.

Ozone trends over the United States at different times of day

NASA Astrophysics Data System (ADS)

Lin, J.; Yan, Y.

2017-12-01

In the United States, the decline of summertime daytime peak ozone in the last 20 years has been clearly connected to reductions in anthropogenic emissions. Yet questions remain on how and through what mechanisms ozone at other times of day have changed over the recent decades. Here we analyze the interannual variability and trends of ozone at different hours of day, using observations from about 1000 US sites during 1990-2014. We find a clear diurnal cycle both in the magnitude of ozone trends and in the relative importance of climate variability versus anthropogenic emissions to ozone changes. Interannual climate variability has mainly been associated with the de-trended fluctuation in the US annual daytime ozone over 1990-2014, with a much smaller effect on the nighttime ozone. Reductions in anthropogenic emissions of nitrogen oxides have led to substantial growth in the US annual average nighttime ozone due to reduced ozone titration, while the summertime daytime ozone has declined. Environmental policymaking might consider further improvements to reduce ozone levels at night and other non-peak hours.

Tropical tropospheric ozone and biomass burning.

PubMed

Thompson, A M; Witte, J C; Hudson, R D; Guo, H; Herman, J R; Fujiwara, M

2001-03-16

New methods for retrieving tropospheric ozone column depth and absorbing aerosol (smoke and dust) from the Earth Probe-Total Ozone Mapping Spectrometer (EP/TOMS) are used to follow pollution and to determine interannual variability and trends. During intense fires over Indonesia (August to November 1997), ozone plumes, decoupled from the smoke below, extended as far as India. This ozone overlay a regional ozone increase triggered by atmospheric responses to the El Niño and Indian Ocean Dipole. Tropospheric ozone and smoke aerosol measurements from the Nimbus 7 TOMS instrument show El Niño signals but no tropospheric ozone trend in the 1980s. Offsets between smoke and ozone seasonal maxima point to multiple factors determining tropical tropospheric ozone variability.

A Reduced Form Model for Ozone Based on Two Decades of ...

EPA Pesticide Factsheets

A Reduced Form Model (RFM) is a mathematical relationship between the inputs and outputs of an air quality model, permitting estimation of additional modeling without costly new regional-scale simulations. A 21-year Community Multiscale Air Quality (CMAQ) simulation for the continental United States provided the basis for the RFM developed in this study. Predictors included the principal component scores (PCS) of emissions and meteorological variables, while the predictand was the monthly mean of daily maximum 8-hour CMAQ ozone for the ozone season at each model grid. The PCS form an orthogonal basis for RFM inputs. A few PCS incorporate most of the variability of emissions and meteorology, thereby reducing the dimensionality of the source-receptor problem. Stochastic kriging was used to estimate the model. The RFM was used to separate the effects of emissions and meteorology on ozone concentrations. by running the RFM with emissions constant (ozone dependent on meteorology), or constant meteorology (ozone dependent on emissions). Years with ozone-conducive meteorology were identified, and meteorological variables best explaining meteorology-dependent ozone were identified. Meteorology accounted for 19% to 55% of ozone variability in the eastern US, and 39% to 92% in the western US. Temporal trends estimated for original CMAQ ozone data and emission-dependent ozone were mostly negative, but the confidence intervals for emission-dependent ozone are much

Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China - Part 2: The roles of anthropogenic emissions and climate variability

NASA Astrophysics Data System (ADS)

Xu, Wanyun; Xu, Xiaobin; Lin, Meiyun; Lin, Weili; Tarasick, David; Tang, Jie; Ma, Jianzhong; Zheng, Xiangdong

2018-01-01

Inter-annual variability and long-term trends in tropospheric ozone are both environmental and climate concerns. Ozone measured at Mt Waliguan Observatory (WLG, 3816 m a.s.l.) on the Tibetan Plateau over the period of 1994-2013 has increased significantly by 0.2-0.3 ppbv yr-1 during spring and autumn but shows a much smaller trend in winter and no significant trend in summer. Here we explore the factors driving the observed ozone changes at WLG using backward trajectory analysis, chemistry-climate model hindcast simulations (GFDL AM3), a trajectory-mapped ozonesonde data set, and several climate indices. A stratospheric ozone tracer implemented in GFDL AM3 indicates that stratosphere-to-troposphere transport (STT) can explain ˜ 60 % of the simulated springtime ozone increase at WLG, consistent with an increase in the NW air-mass frequency inferred from the trajectory analysis. Enhanced STT associated with the strengthening of the mid-latitude jet stream contributes to the observed high ozone anomalies at WLG during the springs of 1999 and 2012. During autumn, observations at WLG are more heavily influenced by polluted air masses originating from South East Asia than in the other seasons. Rising Asian anthropogenic emissions of ozone precursors are the key driver of increasing autumnal ozone observed at WLG, as supported by the GFDL AM3 model with time-varying emissions, which captures the observed ozone increase (0.26 ± 0.11 ppbv yr-1). AM3 simulates a greater ozone increase of 0.38 ± 0.11 ppbv yr-1 at WLG in autumn under conditions with strong transport from South East Asia and shows no significant ozone trend in autumn when anthropogenic emissions are held constant in time. During summer, WLG is mostly influenced by easterly air masses, but these trajectories do not extend to the polluted regions of eastern China and have decreased significantly over the last 2 decades, which likely explains why summertime ozone measured at WLG shows no significant trend despite ozone increases in eastern China. Analysis of the Trajectory-mapped Ozonesonde data set for the Stratosphere and Troposphere (TOST) and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the quasi-biennial oscillation (QBO), the East Asian summer monsoon (EASM), and the sunspot cycle. Our results suggest that the 2-3-, 3-7-, and 11-year periodicities are linked to the QBO, EASM index, and sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

Mars ozone: Mariner 9 revisited

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1994-01-01

The efficacy of the UV spectroscopy technique used by Mariner 9 to remotely measure ozone abundance at Mars is discussed. Previously-inferred ozone abundances could be underestimated by as much as a factor of 3, and much of the observed variability in the ozone abundance could be due to temporal and spatial variability in cloud and dust amount.

Mechanisms Governing Interannual Variability of Stratosphere-to-Troposphere Ozone Transport

NASA Astrophysics Data System (ADS)

Albers, John R.; Perlwitz, Judith; Butler, Amy H.; Birner, Thomas; Kiladis, George N.; Lawrence, Zachary D.; Manney, Gloria L.; Langford, Andrew O.; Dias, Juliana

2018-01-01

Factors governing the strength and frequency of stratospheric ozone intrusions over the Pacific-North American region are considered for their role in modulating tropospheric ozone on interannual timescales. The strength of the association between two major modes of climate variability—the El Niño-Southern Oscillation (ENSO) and the Northern Annular Mode (NAM)—and the amount of ozone contained in stratospheric intrusions are tested in the context of two mechanisms that modulate stratosphere-to-troposphere transport (STT) of ozone: (StratVarO3) the winter season buildup of ozone abundances in the lowermost stratosphere (LMS) and (JetVar) Pacific jet and wave breaking variability during spring. In essence, StratVarO3 corresponds to variability in the amount of ozone per intrusion, while JetVar governs the frequency of intrusions. The resulting analysis, based on two different reanalysis products, suggests that StratVarO3 is more important than JetVar for driving interannual variations in STT of ozone over the Pacific-North American region. In particular, the abundance of ozone in the LMS at the end of winter is shown to be a robust indicator of the amount of ozone that will be contained in stratospheric intrusions during the ensuing spring. Additionally, it is shown that the overall strength of the winter season stratospheric NAM is a useful predictor of ozone intrusion strength. The results also suggest a nuanced relationship between the phase of ENSO and STT of ozone. While ENSO-related jet variability is associated with STT variability, it is wave breaking frequency rather than typical ENSO teleconnection patterns that is responsible for the ENSO-STT relationship.

A climatology of total ozone mapping spectrometer data using rotated principal component analysis

NASA Astrophysics Data System (ADS)

Eder, Brian K.; Leduc, Sharon K.; Sickles, Joseph E.

1999-02-01

The spatial and temporal variability of total column ozone (Ω) obtained from the total ozone mapping spectrometer (TOMS version 7.0) during the period 1980-1992 was examined through the use of a multivariate statistical technique called rotated principal component analysis. Utilization of Kaiser's varimax orthogonal rotation led to the identification of 14, mostly contiguous subregions that together accounted for more than 70% of the total Ω variance. Each subregion displayed statistically unique Ω characteristics that were further examined through time series and spectral density analyses, revealing significant periodicities on semiannual, annual, quasi-biennial, and longer term time frames. This analysis facilitated identification of the probable mechanisms responsible for the variability of Ω within the 14 homogeneous subregions. The mechanisms were either dynamical in nature (i.e., advection associated with baroclinic waves, the quasi-biennial oscillation, or El Niño-Southern Oscillation) or photochemical in nature (i.e., production of odd oxygen (O or O3) associated with the annual progression of the Sun). The analysis has also revealed that the influence of a data retrieval artifact, found in equatorial latitudes of version 6.0 of the TOMS data, has been reduced in version 7.0.

Tropospheric and stratospheric ozone from assimilation of Aura data

NASA Technical Reports Server (NTRS)

Stajner, I.; Wargan, K.; Chang, L.-P.; Hayashi, H.; Pawwson, S.; Froidevaux, L.; Livesey, N.; Bhartia, P. K.

2006-01-01

Ozone is an atmospheric trace gas with multiple impacts on the environment. Global ozone fields are needed for air quality predictions, estimation of the ultraviolet radiation reaching the surface, climate-radiation studies, and may also have an impact on longer-term weather predictions. We estimate global ozone fields in the stratosphere and troposphere by combining the data from EOS Aura satellite with an ozone model using data assimilation. Ozone exhibits a large temporal variability in the lower stratosphere. Our previous work showed that assimilation of satellite data from limb-sounding geometry helps constrain ozone profiles in that region. We assimilated ozone data from the Aura Microwave Limb Sounder (MLS) and the Ozone Monitoring Instrument (OMI) into the ozone system at NASA's Global Modeling and Assimilation Office (GMAO). Ozone is transported within a general circulation model (GCM) which includes parameterizations for stratospheric photochemistry, tropospheric chemistry, and a simple scheme for heterogeneous ozone loss. The focus of this study is on the representation of ozone in the lower stratosphere and tropospheric ozone columns. We plan to extend studies of tropospheric ozone distribution through assimilation of ozone data from the Tropospheric Emission Spectrometer (TES). Comparisons with ozone sondes and occultation data show that assimilation of Aura data reproduces ozone gradients and variability in the lower stratosphere well. We proceed by separating the contributions to temporal changes in the ozone field into those that are due to the model and those that are due to the assimilation of Aura data. The impacts of Aura data are illustrated and their role in the representation of ozone variability in the lower stratosphere and troposphere is shown.

Evaluating the Contribution of Natural Variability and Climate Model Response to Uncertainty in Projections of Climate Change Impacts on U.S. Air Quality

EPA Science Inventory

We examine the effects of internal variability and model response in projections of climate impacts on U.S. ground-level ozone across the 21st century using integrated global system modeling and global atmospheric chemistry simulations. The impact of climate change on air polluti...

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.

Statistical methods and regression analysis of stratospheric ozone and meteorological variables in Isfahan

NASA Astrophysics Data System (ADS)

Hassanzadeh, S.; Hosseinibalam, F.; Omidvari, M.

2008-04-01

Data of seven meteorological variables (relative humidity, wet temperature, dry temperature, maximum temperature, minimum temperature, ground temperature and sun radiation time) and ozone values have been used for statistical analysis. Meteorological variables and ozone values were analyzed using both multiple linear regression and principal component methods. Data for the period 1999-2004 are analyzed jointly using both methods. For all periods, temperature dependent variables were highly correlated, but were all negatively correlated with relative humidity. Multiple regression analysis was used to fit the meteorological variables using the meteorological variables as predictors. A variable selection method based on high loading of varimax rotated principal components was used to obtain subsets of the predictor variables to be included in the linear regression model of the meteorological variables. In 1999, 2001 and 2002 one of the meteorological variables was weakly influenced predominantly by the ozone concentrations. However, the model did not predict that the meteorological variables for the year 2000 were not influenced predominantly by the ozone concentrations that point to variation in sun radiation. This could be due to other factors that were not explicitly considered in this study.

Identifying controlling factors of ground-level ozone levels over southwestern Taiwan using a decision tree

NASA Astrophysics Data System (ADS)

Chu, Hone-Jay; Lin, Chuan-Yao; Liau, Churn-Jung; Kuo, Yi-Ming

2012-12-01

Kaohsiung City and the suburban region of southwestern Taiwan have suffered from severe air pollution since becoming the largest center of heavy industry in Taiwan. The complex process of ozone (O3) formation and its precursor compounds (the volatile organic compounds (VOCs) and nitrogen oxide (NOx) emissions), accompanied by meteorological conditions, make controlling ozone difficult. Using a decision tree is especially appropriate for analyzing time series data that contain ozone levels and meteorological and explanatory variables for ozone formation. Results show that dominant variables such as temperature, wind speed, VOCs, and NOx can play vital roles in describing ozone variations among observations. That temperature and wind speed are highly correlated with ozone levels indicates that these meteorological conditions largely affect ozone variability. The results also demonstrate that spatial heterogeneity of ozone patterns are in coastal and inland areas caused by sea-land breeze and pollutant sources during high ozone episodes over southwestern Taiwan. This study used a decision tree to obtain quantitative insight into spatial distributions of precursor compound emissions and effects of meteorological conditions on ozone levels that are useful for refining monitoring plans and developing management strategies.

Long-term Measurements of Summer-time Ozone at the Walnut Grove Tower - Understanding Trends in the Boundary Layer

NASA Astrophysics Data System (ADS)

Mahmud, A.; Di, P.; Mims, D.; Avise, J.; DaMassa, J.; Kaduwela, A. P.

2015-12-01

The California Air Resources Board (CARB) has been monitoring boundary layer ozone at the Walnut Grove Tower (WGT) since 1996 for investigating regional transport and vertical profile. Walnut Grove is located between Sacramento and Stockton, CA in the Sacramento - San Joaquin Delta. Sampling inlets are positioned at 30-ft, 400-ft, 800-ft, 1200-ft and 1600-ft levels of the 2000-ft tower, which is one of the tallest monitoring towers in the Western US. Ozone, ambient temperature, wind speed, and wind direction are simultaneously measured at each level, and reported as hourly averages. The current study included analyses of available ozone and corresponding meteorological data for the months of June - September from 1996 - 2014 with objectives to: 1) explore trends and inter-annual variability of ozone, 2) examine any correlations between ozone and meteorological parameters, 3) understand interactions of ozone measured at various levels, and 4) assess how well a regulatory state-of-the-science air quality model such as the Community Multi-scale Air Quality Model (CMAQ) captures observation. Daily 1-hr maximum ozone has been consistently decreasing during the 1996 - 2014 period at a rate of ~1 ppb per year. This indicates that CARB's measures to control ambient ozone have been effective over the past years. Evolution of the vertical profile throughout the day shows that ozone is fairly homogeneously mixed between 1 - 5 pm, when mixing height typically reaches the maximum. Ozone at 30-ft shows the greatest variability because of its proximity to the ground and emissions sources - rises faster during morning hours (7 - 10 am) and declines more rapidly during evening hours (7 - 10 pm) compared to other levels. Air masses reaching the tower are predominantly southwesterly (247 - 257 deg.) at the bottom, and southwesterly to slightly northwesterly (254 - 302 deg.) at top levels. Daily 1-hr maximum ozone was negatively correlated with wind speed (i.e. ozone was high under low wind condition) and positively correlated with ambient temperature (i.e. ozone was high under high temperature condition) during ~40% and ~50% of the time, respectively. A modeling exercise for Jun - Sep of 2012 shows that CMAQ captures the observed evolution and vertical mixing of ozone throughout the day quite well in the boundary layer.

Soil Moisture-Atmosphere Feedbacks on Atmospheric Tracers: The Effects of Soil Moisture on Precipitation and Near-Surface Chemistry

NASA Astrophysics Data System (ADS)

Tawfik, Ahmed B.

The atmospheric component is described by rapid fluctuations in typical state variables, such as temperature and water vapor, on timescales of hours to days and the land component evolves on daily to yearly timescales. This dissertation examines the connection between soil moisture and atmospheric tracers under varying degrees of soil moisture-atmosphere coupling. Land-atmosphere coupling is defined over the United States using a regional climate model. A newly examined soil moisture-precipitation feedback is identified for winter months extending the previous summer feedback to colder temperature climates. This feedback is driven by the freezing and thawing of soil moisture, leading to coupled land-atmosphere conditions near the freezing line. Soil moisture can also affect the composition of the troposphere through modifying biogenic emissions of isoprene (C5H8). A novel first-order Taylor series decomposition indicates that isoprene emissions are jointly driven by temperature and soil moisture in models. These compounds are important precursors for ozone formation, an air pollutant and a short-lived forcing agent for climate. A mechanistic description of commonly observed relationships between ground-level ozone and meteorology is presented using the concept of soil moisture-temperature coupling regimes. The extent of surface drying was found to be a better predictor of ozone concentrations than temperature or humidity for the Eastern U.S. This relationship is evaluated in a coupled regional chemistry-climate model under several land-atmosphere coupling and isoprene emissions cases. The coupled chemistry-climate model can reproduce the observed soil moisture-temperature coupling pattern, yet modeled ozone is insensitive to changes in meteorology due to the balance between isoprene and the primary atmospheric oxidant, the hydroxyl radical (OH). Overall, this work highlights the importance of soil moisture-atmosphere coupling for previously neglected cold climate regimes, controlling isoprene emissions variability, and providing a processed-based description of observed ozone-meteorology relationships. From the perspective of ozone air quality, the lack of sensitivity of ozone to meteorology suggests a systematic deficiency in chemistry models in high isoprene emission regions. This shortcoming must be addressed to better estimate tropospheric ozone radiative forcing and to understanding how ozone air quality may respond to future warming.

Improving assessments of tropospheric ozone injury to Mediterranean montane conifer forests in California (USA) and Catalonia (Spain) with GIS models related to plant water relations

NASA Astrophysics Data System (ADS)

Kefauver, Shawn C.; Peñuelas, Josep; Ustin, Susan L.

2012-12-01

The impacts of tropospheric ozone on conifer health in the Sierra Nevada of California, USA, and the Pyrenees of Catalonia, Spain, were measured using field assessments and GIS variables of landscape gradients related to plant water relations, stomatal conductance and hence to ozone uptake. Measurements related to ozone injury included visible chlorotic mottling, needle retention, needle length, and crown depth, which together compose the Ozone Injury Index (OII). The OII values observed in Catalonia were similar to those in California, but OII alone correlated poorly to ambient ozone in all sites. Combining ambient ozone with GIS variables related to landscape variability of plant hydrological status, derived from stepwise regressions, produced models with R2 = 0.35, p = 0.016 in Catalonia, R2 = 0.36, p < 0.001 in Yosemite and R2 = 0.33, p = 0.007 in Sequoia/Kings Canyon National Parks in California. Individual OII components in Catalonia were modeled with improved success compared to the original full OII, in particular visible chlorotic mottling (R2 = 0.60, p < 0.001). The results show that ozone is negatively impacting forest health in California and Catalonia and also that modeling ozone injury improves by including GIS variables related to plant water relations.

Discoveries about Tropospheric Ozone Pollution from Satellite and Sounding

NASA Technical Reports Server (NTRS)

Thompson, Anne M.

2004-01-01

We have been producing near-real time tropospheric ozone satellite maps from the TOMS (Total Ozone Mapping Spectrometer) sensor since 1997. This is most readily done for the tropics, where the stratospheric and tropospheric ozone column amounts can be discriminated readily. Maps for 1996-2000 for the operational Earth-Probe instrument reside at: chttp://www.atmos.umd.edu/-trope>. Pollution in the tropics is influenced by biomass burning and by transport patterns that favor recirculation and in other cases reflect climate variability like the El-Nino-Southern Oscillation [Thompson et al., 2001]. Time permitting, examples of mid-latitude, intercontinental transport of ozone pollution sensed by TOMS will be shown. The satellite view of chemical-dynamical interactions in tropospheric ozone is not adequate to capture vertical variability. Thus, in 1998, NASA's Goddard Space Flight Center and a team of international sponsors established the SHADOZ (Southern Hemisphere ADditional OZonesondes) project to address the gap in tropical ozone soundings. SHADOZ augments launches and provides a public archive of ozonesonde data from twelve tropical stations at http://croc.gsfc.nasa.gov/shadoz. Further insights into the role of chemical and dynamical influences have emerged from the first 4-5 years of SHADOZ data (less than 2000 ozone profiles): (a) highly variable tropospheric ozone; (b) a zonal wave-one pattern in tropospheric column ozone; (c) convective variability affects tropospheric ozone over the Indian and Pacific Ocean; (d) a "tropical Atlantic Paradox" appears in December-January-February.

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.

The seasonality and geographic dependence of ENSO impacts on U.S. surface ozone variability

NASA Astrophysics Data System (ADS)

Xu, Li; Yu, Jin-Yi; Schnell, Jordan L.; Prather, Michael J.

2017-04-01

We examine the impact of El Niño-Southern Oscillation (ENSO) on surface ozone abundance observed over the continental United States (U.S.) during 1993-2013. The monthly ozone decreases (increases) during El Niño (La Niña) years with amplitude up to 1.8 ppb per standard deviation of Niño 3.4 index. The largest ENSO influences occur over two southern U.S. regions during fall when the ENSO develops and over two western U.S. regions during the winter to spring after the ENSO decays. ENSO affects surface ozone via chemical processes during warm seasons in southern regions, where favorable meteorological conditions occur, but via dynamic transport during cold seasons in western regions, where the ENSO-induced circulation variations are large. The geographic dependence and seasonality of the ENSO impacts imply that regulations regarding air quality and its exceedance need to be adjusted for different seasons and U.S. regions to account for the ENSO-driven patterns in surface ozone.

Effect of noise in principal component analysis with an application to ozone pollution

NASA Astrophysics Data System (ADS)

Tsakiri, Katerina G.

This thesis analyzes the effect of independent noise in principal components of k normally distributed random variables defined by a covariance matrix. We prove that the principal components as well as the canonical variate pairs determined from joint distribution of original sample affected by noise can be essentially different in comparison with those determined from the original sample. However when the differences between the eigenvalues of the original covariance matrix are sufficiently large compared to the level of the noise, the effect of noise in principal components and canonical variate pairs proved to be negligible. The theoretical results are supported by simulation study and examples. Moreover, we compare our results about the eigenvalues and eigenvectors in the two dimensional case with other models examined before. This theory can be applied in any field for the decomposition of the components in multivariate analysis. One application is the detection and prediction of the main atmospheric factor of ozone concentrations on the example of Albany, New York. Using daily ozone, solar radiation, temperature, wind speed and precipitation data, we determine the main atmospheric factor for the explanation and prediction of ozone concentrations. A methodology is described for the decomposition of the time series of ozone and other atmospheric variables into the global term component which describes the long term trend and the seasonal variations, and the synoptic scale component which describes the short term variations. By using the Canonical Correlation Analysis, we show that solar radiation is the only main factor between the atmospheric variables considered here for the explanation and prediction of the global and synoptic scale component of ozone. The global term components are modeled by a linear regression model, while the synoptic scale components by a vector autoregressive model and the Kalman filter. The coefficient of determination, R2, for the prediction of the synoptic scale ozone component was found to be the highest when we consider the synoptic scale component of the time series for solar radiation and temperature. KEY WORDS: multivariate analysis; principal component; canonical variate pairs; eigenvalue; eigenvector; ozone; solar radiation; spectral decomposition; Kalman filter; time series prediction

Dynamical variability in the modelling of chemistry-climate interactions.

PubMed

Pyle, J A; Braesicke, P; Zeng, G

2005-01-01

We have used a version of the Met Office's climate model, into which we have introduced schemes for atmospheric chemistry, to study chemistry-dynamics-climate interactions. We have considered the variability of the stratospheric polar vortex, whose behaviour influences stratospheric ozone loss and will affect ozone recovery. In particular, we analyse the dynamical control of high latitude ozone in a model version which includes an assimilation of the equatorial quasi-biennial oscillation (QBO), demonstrating the stability of the linear relation between vortex strength and high latitude ozone. We discuss the effect of interactive model ozone on polar stratospheric cloud (PSC) area/volume and winter-spring stratospheric ozone loss in the northern hemisphere. In general we find larger polar ozone losses calculated in those model integrations in which modelled ozone is used interactively in the radiation scheme, even though we underestimate the slope of the ozone loss per PSC volume relation derived from observations. We have also looked at the influence of changing stratosphere-to-troposphere exchange on the tropospheric oxidizing capacity and, in particular, have considered the variability of tropospheric composition under different climate regimes (El Niño/La Niña, etc.). Focusing on the UT/LS, we show the response of ozone to El Niño in two different model set-ups (tropospheric/ stratospheric). In the stratospheric model set-up we find a distinct signal in the lower tropical stratosphere, which shows an anti-correlation between the Niño 3 index and the ozone column amount. In contrast ozone generally increases in the upper troposphere of the tropospheric model set-up after an El Niño. Understanding future trends in stratospheric ozone and tropospheric oxidizing capacity requires an understanding of natural variability, which we explore here.

The Response of Tropospheric Ozone to ENSO in Observations and a Chemistry-Climate Simulation

NASA Technical Reports Server (NTRS)

Oman, L. D.; Douglass, A. R.; Ziemke, J. R.; Waugh, D. W.; Rodriguez, J. M.; Nielsen, J. E.

2012-01-01

The El Nino-Southern Oscillation (ENSO) is the dominant mode of tropical variability on interannual time scales. ENSO appears to extend its influence into the chemical composition of the tropical troposphere. Recent results have revealed an ENSO induced wave-l anomaly in observed tropical tropospheric column ozone. This results in a dipole over the western and eastern tropical Pacific, whereby differencing the two regions produces an ozone anomaly with an extremely high correlation to the Nino 3.4 Index. We have successfully reproduced this result using the Goddard Earth Observing System Version 5 (GEOS-5) general circulation model coupled to a comprehensive stratospheric and tropospheric chemical mechanism forced with observed sea surface temperatures over the past 25 years. An examination of the modeled ozone field reveals the vertical contributions of tropospheric ozone to the column over the western and eastern Pacific region. We will show targeted comparisons with observations from NASA's Aura satellite Microwave Limb Sounder (MLS), and the Tropospheric Emissions Spectrometer (TES) to provide insight into the vertical structure of ozone changes. The tropospheric ozone response to ENSO could be a useful chemistry-climate model evaluation tool and should be considered in future modeling assessments.

[A Study of Data From the Photochemistry of Ozone Loss in the Arctic Region In Summer (POLARIS) Mission

NASA Technical Reports Server (NTRS)

Newman, Paul A.; Fahey, David W.; Brune, William H.; Kurylo, Michael J.; Kawa, S. Randolph

1999-01-01

The Photochemistry of Ozone Loss in the Arctic Region In Summer (POLARIS) mission was designed to investigate the natural summer decrease of stratospheric ozone levels. Both polar regions have large and distinct annual cycles of ozone column amounts. In northern spring, the average level is over 450 Dobson units (DU), decreasing to less than 275 DU by September. In order to cover this period of ozone decrease, POLARIS was conducted in three deployment phases from Fairbanks, Alaska, (650N) during the summer of 1997. The principal measurement platforms were the NASA ER-2 high-altitude aircraft and stratospheric balloons. Additional measurements were provided by ground-based instruments, sondes, and satellites. POLARIS observations included ozone, meteorological variables, particles, long-lived chemicals, and short-lived radicals. During the field deployments, several modeling and theoretical groups participated in flight planning and data evaluation activities. The interpretive studies in this Special Section of the Journal of Geophysical Research are a first comprehensive examination of the POLARIS data set, addressing stratospheric ozone abundances and its changes; the role of aerosols; details of the photochemistry of reactive species; transport of stratospheric air and the correlations of long-lived species; and measurement intercomparisons.

Variability in total ozone associated with baroclinic waves

NASA Technical Reports Server (NTRS)

Mote, Philip W.; Holton, James R.; Wallace, John M.

1991-01-01

One-point regression maps of total ozone formed by regressing the time series of bandpass-filtered geopotential height data have been analyzed against Total Ozone Mapping Spectrometer data. Results obtained reveal a strong signature of baroclinic waves in the ozone variability. The regressed patterns are found to be similar in extent and behavior to the relative vorticity patterns reported by Lim and Wallace (1991).

A two-dimensional photochemical model of the atmosphere. I Chlorocarbon emissions and their effect on stratospheric ozone

NASA Technical Reports Server (NTRS)

Gidel, L. T.; Crutzen, P. J.; Fishman, J.

1983-01-01

A two-dimensional photochemical model is used to examine changes to the ozone layer caused by emissions of CFCl3, CF2Cl2, CH3CCl3 and CCl4. The influence of a possible secular increase in tropospheric methane up to 2 percent per year was found to be small, although it acts to mask decreases in total ozone caused by the chlorocarbons. Increasing NO(x) emissions caused by industralization also tend to mask decreases in total ozone and may have caused total ozone to increase by about 1 percent. The model-calculated ozone decreases are estimated to be about 3 percent by 1980. This estimate is higher than estimates by similar models, although it is noted that CCl4 and CH3CCl3 emissions are included in the model in addition to CFCl3 and CF2Cl2. This is significant because the model indicates that CCl4 has dominated the ozone depletions so far, and knowledge of the historical emission rate of CCl4 to the atmosphere is incomplete. There remain sufficient significant disagreements between theoretical and observed concentrations and variabilities, particularly for odd nitrogen and ClO, to caution against assigning too much confidence in the calculated ozone depletion.

Net ozone photochemical production over the eastern and central North Pacific as inferred from GTE/CITE 1 observations during fall 1983

NASA Technical Reports Server (NTRS)

Chameides, W. L.; Davis, D. D.; Rodgers, M. O.; Bradshaw, J.; Sandholm, S.; Sachse, G.; Hill, G.; Gregory, G.

1987-01-01

The role of photochemistry in the budget of tropospheric ozone is studied. Measurements of O3, NO, CO, H2O vapor, and temperature obtained during the fall of 1983 during the GTE/CITE project over the eastern and central North Pacific Ocean are analyzed. The effect of altitude on the measurements is discussed. The analysis reveals a correlation between ozone and NO levels; both increase in concentration and variability with altitude. It is observed that an additional source of secondary importance associated wih CO-rich air parcels exists. A photochemical model is utilized to calculate the net rate of ozone production by photochemical reactions. A net photochemical source of ozone in the free troposphere and a net sink in the boundary layer are detected. The relation between the ozone source in the free troposphere and NO is examined. It is estimated that photochemistry provides a net ozone source to the free troposphere overlying the eastern and central North Pacific Ocean of about 5 x 10 to the 10th molecules/sq cm sec and a net sink of ozone to the boundary layer overlying this region of about 3 x 10 to the 10th molecules/sq cm sec.

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.

Estimating the Tropospheric Ozone Distribution by the Assimilation of Satellite Data

NASA Technical Reports Server (NTRS)

Hayashi, Hiroo; Stajner, Ivanka; Winslow, Nathan; Jones, Dylan B. A.; Pawson, Steven; Thompson, Anne M.

2003-01-01

Tropospheric ozone is important to the environment, because it acts as a strong oxidant to control the concentrations of many reduced gases (methane, carbon monoxide, ... ), its radiative forcing plays a significant role in the greenhouse effect, and direct contact with ozone is harmful to human health. Tropospheric ozone, whose main sources are intrusion from the stratosphere and chemical production from source gases associated with urban pollution or biomass burning, varies on a wide range of spatial and temporal scales. Its transport and chemistry can be influenced by weather, seasonal, or multiannual variability. Despite the importance of tropospheric ozone, it contributes only about 10% of the total ozone loading in the atmosphere. Consequently, satellite instruments lose sensitivity below the stratospheric ozone peak, and provide little information about middle and lower tropospheric ozone. This talk will discuss recent modifications made to the satellite ozone data assimilation system at NASA's Data Assimilation Office (DAO) in order to provide better tropospheric ozone columns and profiles. We use a version of the system that assimilates only the data from the Solar Backscatter UltraViolet/2 (SBUV/2) instrument. The quality of the assimilated ozone in the tropical troposphere is evaluated by comparison with independent observations obtained from the Southern Hemispheric Additional Ozonesondes (SHADOZ) network. It is shown that the quality of ozone fields is sensitive to the winds used in the transport model. Increasing the vertical resolution of the model also has a beneficial impact. The assimilated ozone in the lower troposphere was substantially improved by inclusion of tropospheric ozone production, loss, and dry deposition rates from the Harvard GEOS-CHEM model. The mechanisms behind these results will be examined and the implications for our understanding of tropospheric ozone will be discussed.

Discoveries about Tropical Tropospheric Ozone from Satellite and SHADOZ (Southern Hemisphere Additional Ozonesondes) and a Future Perspective on NASA's Ozone Sensors

NASA Technical Reports Server (NTRS)

Thompson, Anne

2003-01-01

We have been producing near-real tropical tropospheric ozone ('TTO') data from TOMS since 1997 with Prof. Hudson and students at the University of Maryland. Maps for 1996-2000 for the operational Earth-Probe instrument reside at: . We also have archived 'TTO' data from the Nimbus 7/TOMS satellite (1979-1992). The tropics is a region strongly influenced by natural variability and anthropogenic activity and the satellite data have been used to track biomass burning pollution and to detect interannual variability and climate signals in ozone. We look forward to future ozone sensors from NASA; four will be launched in 2004 as part of the EOS AURA Mission. The satellite view of chemical-dynamical interactions in tropospheric ozone is not adequate to capture vertical variability. Thus, in 1998, NASA's Goddard Space Flight Center, NOAA's Climate Monitoring and Diagnostics Laboratory (CMDL) and a team of international sponsors established the SHADOZ (Southern Hemisphere ADditional OZonesondes) project to address the gap in tropical ozone soundings. SHADOZ augments launches at selected sites and provides a public archive of ozonesonde data from twelve tropical and subtropical stations at http://croc.nsfc.nasa.gov/shadoz. The stations are: Ascension Island; Nairobi, Kenya; Irene, South Africa; R,union Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil, Malindi, Kenya; Paramaribo, Surinam. From the first 3-4 years of data (presently greater than 1700 sondes), the following features emerge: (a) highly variable tropospheric ozone; (b) a zonal wave-one pattern in tropospheric column ozone; (c) tropospheric ozone variability over the Indian and Pacific Ocean displays strong convective signatures.

Variability in Tropical Tropospheric Ozone as Observed by SHADOZ

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacquelyn C.; Coetzee, Geert J. R.; Chatfield, Robert B.; Hudson, Robert D.

2004-01-01

The SHADOZ (Southern Hemisphere Additional Ozonesondes) ozone sounding network was initiated in 1998 to improve the coverage of tropical in-situ ozone measurements for satellite validation, algorithm development and related process studies. Over 2000 soundings have been archived at the central website, , for 12 stations: Ascension Island; Nairobi and Malindi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil; Paramaribo, Surinam. Some results to date indicate reliability of the measurement and highly variable interactions between ozone and tropical meteorology. For example: 1. By using ECC sondes with similar procedures, 5-10% accuracy and precision (1-sigma) of the sonde total ozone measurement was achieved [Thompson et al., 2003al; 2. Week-to-week variability in tropospheric ozone is so great that statistics are frequently not Gaussian and most stations vary up to a factor of 3 in column amount over the course of a year [Thompson et al., 2002b]. 3. Longitudinal variability in tropospheric ozone profiles is a consistent feature, with a 10- 15 DU column-integrated difference between Atlantic and Pacific sites; this is the cause of the zonal wave-one feature in total ozone [Shiotani, 1992]. The ozone record from Paramaribo, Surinam (6N, 55W) is a marked contrast to southern tropical ozone because Surinam is often north of the Intertropical Convergence Zone. Interpretations of SHADOZ time-series and approaches to classification suggested by SHADOZ data over Africa and the Indian Ocean will be described.

A Decadal (2004-2014) Analysis of Global-to-Regional Tropospheric Ozone Column Trends Using GFDL-AM3 Model Simulations and OMI Observations

NASA Astrophysics Data System (ADS)

Huang, G.; Liu, X.; Lin, M.; Ziemke, J. R.; Chance, K.; Zoogman, P.; Sun, K.

2017-12-01

Tropospheric ozone is a greenhouse gas, biological irritant, and significant source of highly reactive hydroxyl radicals, which remove many hazardous trace gases from the atmosphere. The decadal trend of tropospheric ozone columns (TOCs) can be influenced by many factors including anthropogenic and natural emissions of ozone precursors, large-scale atmospheric circulation patterns, and stratosphere-to-troposphere exchange. Since 2000, anthropogenic emissions of NOx have tended to shift from North America and Europe to Asia. This rapid shift has been implicated in raising background tropospheric ozone burden. However, large meteorologically-driven ozone variability complicates the unambiguous attribution of TOC trends calculated over short periods. In this study, we examine global-to-regional TOC trends during 2004-2014 using two independent satellite retrievals from OMI SAO (Smithsonian Astrophysical Observatory) and OMI/MLS, and interpret the results with a suite of GFDL-AM3 chemistry-climate model hindcasts designed to isolate the response of ozone to anthropogenic emissions, wildfires, and meteorology. Generally, OMI SAO, OMI/MLS and GFDL-AM3 BASE simulations agree on regional hot spots of TOC trends. On the regional scale, we find strong positive TOC trends during 2004-2014 in Mid-East (0.3-0.6 DU yr-1), South Asia (0.3-0.5 DU yr-1), Southeast Asia, East Asia ( 0.1-0.6 DU yr-1) and Central Africa ( 0.6 DU yr-1). Our initial analysis indicates that meteorological variability and anthropogenic emission trends play equally important roles in the positive TOC trends in East Asia and on a global scale during 2004-2014. We are working to investigate the potential influences from lightening NOx emissions, forest fires, and the stratosphere-to-troposphere exchange.

Multi-year assimilation of IASI and MLS ozone retrievals: variability of tropospheric ozone over the tropics in response to ENSO

NASA Astrophysics Data System (ADS)

Peiro, Hélène; Emili, Emanuele; Cariolle, Daniel; Barret, Brice; Le Flochmoën, Eric

2018-05-01

The Infrared Atmospheric Sounder Instrument (IASI) allows global coverage with very high spatial resolution and its measurements are promising for long-term ozone monitoring. In this study, Microwave Limb Sounder (MLS) O3 profiles and IASI O3 partial columns (1013.25-345 hPa) are assimilated in a chemistry transport model to produce 6-hourly analyses of tropospheric ozone for 6 years (2008-2013). We have compared and evaluated the IASI-MLS analysis and the MLS analysis to assess the added value of IASI measurements. The global chemical transport model MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) has been used with a linear ozone chemistry scheme and meteorological forcing fields from ERA-Interim (ECMWF global reanalysis) with a horizontal resolution of 2° × 2° and 60 vertical levels. The MLS and IASI O3 retrievals have been assimilated with a 4-D variational algorithm to constrain stratospheric and tropospheric ozone respectively. The ozone analyses are validated against ozone soundings and tropospheric column ozone (TCO) from the OMI-MLS residual method. In addition, an Ozone ENSO Index (OEI) is computed from the analysis to validate the TCO variability during the ENSO events. We show that the assimilation of IASI reproduces the variability of tropospheric ozone well during the period under study. The variability deduced from the IASI-MLS analysis and the OMI-MLS measurements are similar for the period of study. The IASI-MLS analysis can reproduce the extreme oscillation of tropospheric ozone caused by ENSO events over the tropical Pacific Ocean, although a correction is required to reduce a constant bias present in the IASI-MLS analysis.

Enhancement of free tropospheric ozone production by deep convection

NASA Technical Reports Server (NTRS)

Pickering, Kenneth E.; Thompson, Anne M.; Scala, John R.; Tao, Wei-Kuo; Simpson, Joanne

1994-01-01

It is found from model simulations of trace gas and meteorological data from aircraft campaigns that deep convection may enhance the potential for photochemical ozone production in the middle and upper troposphere by up to a factor of 60. Examination of half a dozen individual convective episodes show that the degree of enhancement is highly variable. Factors affecting enhancement include boundary layer NO(x) mixing ratios, differences in the strength and structure of convective cells, as well as variation in the amount of background pollution already in the free troposphere.

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.

An intercomparison of multidecadal observational and reanalysis data sets for global total ozone trends and variability analysis

NASA Astrophysics Data System (ADS)

Bai, Kaixu; Chang, Ni-Bin; Shi, Runhe; Yu, Huijia; Gao, Wei

2017-07-01

A four-step adaptive ozone trend estimation scheme is proposed by integrating multivariate linear regression (MLR) and ensemble empirical mode decomposition (EEMD) to analyze the long-term variability of total column ozone from a set of four observational and reanalysis total ozone data sets, including the rarely explored ERA-Interim total ozone reanalysis, from 1979 to 2009. Consistency among the four data sets was first assessed, indicating a mean relative difference of 1% and root-mean-square error around 2% on average, with respect to collocated ground-based total ozone observations. Nevertheless, large drifts with significant spatiotemporal inhomogeneity were diagnosed in ERA-Interim after 1995. To emphasize long-term trends, natural ozone variations associated with the solar cycle, quasi-biennial oscillation, volcanic aerosols, and El Niño-Southern Oscillation were modeled with MLR and then removed from each total ozone record, respectively, before performing EEMD analyses. The resulting rates of change estimated from the proposed scheme captured the long-term ozone variability well, with an inflection time of 2000 clearly detected. The positive rates of change after 2000 suggest that the ozone layer seems to be on a healing path, but the results are still inadequate to conclude an actual recovery of the ozone layer, and more observational evidence is needed. Further investigations suggest that biases embedded in total ozone records may significantly impact ozone trend estimations by resulting in large uncertainty or even negative rates of change after 2000.

"Cloud Slicing" : A New Technique to Derive Tropospheric Ozone Profile Information from Satellite Measurements

NASA Technical Reports Server (NTRS)

Ziemke, J. R.; Chandra, S.; Bhartia, P. K.; Einaudi, Franco (Technical Monitor)

2000-01-01

A new technique denoted cloud slicing has been developed for estimating tropospheric ozone profile information. All previous methods using satellite data were only capable of estimating the total column of ozone in the troposphere. Cloud slicing takes advantage of the opaque property of water vapor clouds to ultraviolet wavelength radiation. Measurements of above-cloud column ozone from the Nimbus 7 total ozone mapping spectrometer (TOMS) instrument are combined together with Nimbus 7 temperature humidity and infrared radiometer (THIR) cloud-top pressure data to derive ozone column amounts in the upper troposphere. In this study tropical TOMS and THIR data for the period 1979-1984 are analyzed. By combining total tropospheric column ozone (denoted TCO) measurements from the convective cloud differential (CCD) method with 100-400 hPa upper tropospheric column ozone amounts from cloud slicing, it is possible to estimate 400-1000 hPa lower tropospheric column ozone and evaluate its spatial and temporal variability. Results for both the upper and lower tropical troposphere show a year-round zonal wavenumber 1 pattern in column ozone with largest amounts in the Atlantic region (up to approx. 15 DU in the 100-400 hPa pressure band and approx. 25-30 DU in the 400-1000 hPa pressure band). Upper tropospheric ozone derived from cloud slicing shows maximum column amounts in the Atlantic region in the June-August and September-November seasons which is similar to the seasonal variability of CCD derived TCO in the region. For the lower troposphere, largest column amounts occur in the September-November season over Brazil in South America and also southern Africa. Localized increases in the tropics in lower tropospheric ozone are found over the northern region of South America around August and off the west coast of equatorial Africa in the March-May season. Time series analysis for several regions in South America and Africa show an anomalous increase in ozone in the lower troposphere around the month of March which is not observed in the upper troposphere. The eastern Pacific indicates weak seasonal variability of upper, lower, and total tropospheric ozone compared to the western Pacific which shows largest TCO amounts in both hemispheres around spring months. Ozone variability in the western Pacific is expected to have greater variability caused by strong convection, pollution and biomass burning, land/sea contrast and monsoon developments.

Evaluation of ozone hindcasts: optimal data sets to use, and results from simulations with the GMI model for 1990-2010.

NASA Astrophysics Data System (ADS)

Logan, J. A.; Megretskaia, I.; Liu, J.; Rodriguez, J. M.; Strahan, S. E.; Damon, M.; Steenrod, S. D.

2012-12-01

Simulations of atmospheric composition in the recent past (hindcasts) are a valuable tool for determining the causes of interannual variability (IAV) and trends in tropospheric ozone, including factors such as anthropogenic emissions, biomass burning, stratospheric input, and variability in meteorology. We will review the ozone data sets (balloon, satellite, and surface) that are the most reliable for evaluating hindcasts, and demonstrate their application with the GMI model. The GMI model is driven by the GEOS-5/MERRA reanalysis and includes both stratospheric and tropospheric chemistry. Preliminary analysis of a simulation for 1990-2010 using constant fossil fuel emissions is promising. The model reproduces the recent interannual variability (IAV) in ozone in the lowermost stratosphere seen in MLS and sonde data, as well as the IAV seen in sonde data in the lower stratosphere since 1995, and captures much of the IAV and short-term trends in surface ozone at remote sites, showing the influence of variability in dynamics. There was considerable IAV in ozone in the lowermost stratosphere in the Aura period, but almost none at European alpine sites in winter/spring, when ozone at 150 hPa has been shown to be correlated with that at 700 hPa in earlier years. The model matches the IAV in alpine ozone in Europe in July-September, including the high values in heat-waves, showing the role of variability in meteorology. A focus on IAV in each season is essential. The model matches IAV in MLS in the upper troposphere, TES tropical ozone, and the tropospheric ozone column (OMI/MLS) the best in tSropical regions controlled by ENSO related changes in dynamics. This study, combined with sensitivity simulations with changes to emissions, and simulations with passive tracers (see Abstract by Rodriguez et al. Session A76), lays the foundations for assessment of the mechanisms that have influenced tropospheric ozone in the past two decades.

The characterization of an air pollution episode using satellite total ozone measurements

NASA Technical Reports Server (NTRS)

Fishman, Jack; Shipham, Mark C.; Vukovich, Fred M.; Cahoon, Donald R.

1987-01-01

A case study is presented which demonstrates that measurements of total ozone from a space-based platform can be used to study a widespread air pollution episode over the southeastern U.S. In particular, the synoptic-scale distribution of surface-level ozone obtained from an independent analysis of ground-based monitoring stations appears to be captured by the synoptic-scale distribution of total ozone, even though about 90 percent of the total ozone is in the stratosphere. Additional analyses of upper air meteorological data, other satellite imagery, and in situ aircraft measurements of ozone likewise support the fact that synoptic-scale variability of tropospheric ozone is primarily responsible for the observed variability in total ozone under certain conditions. The use of the type of analysis discussed in this study may provide an important technique for understanding the global budget of tropospheric ozone.

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. © 2015, The International Biometric Society.

Extreme value modeling for the analysis and prediction of time series of extreme tropospheric ozone levels: a case study.

PubMed

Escarela, Gabriel

2012-06-01

The occurrence of high concentrations of tropospheric ozone is considered as one of the most important issues of air management programs. The prediction of dangerous ozone levels for the public health and the environment, along with the assessment of air quality control programs aimed at reducing their severity, is of considerable interest to the scientific community and to policy makers. The chemical mechanisms of tropospheric ozone formation are complex, and highly variable meteorological conditions contribute additionally to difficulties in accurate study and prediction of high levels of ozone. Statistical methods offer an effective approach to understand the problem and eventually improve the ability to predict maximum levels of ozone. In this paper an extreme value model is developed to study data sets that consist of periodically collected maxima of tropospheric ozone concentrations and meteorological variables. The methods are applied to daily tropospheric ozone maxima in Guadalajara City, Mexico, for the period January 1997 to December 2006. The model adjusts the daily rate of change in ozone for concurrent impacts of seasonality and present and past meteorological conditions, which include surface temperature, wind speed, wind direction, relative humidity, and ozone. The results indicate that trend, annual effects, and key meteorological variables along with some interactions explain the variation in daily ozone maxima. Prediction performance assessments yield reasonably good results.

The Extrapolar SWIFT model (version 1.0): fast stratospheric ozone chemistry for global climate models

NASA Astrophysics Data System (ADS)

Kreyling, Daniel; Wohltmann, Ingo; Lehmann, Ralph; Rex, Markus

2018-03-01

The Extrapolar SWIFT model is a fast ozone chemistry scheme for interactive calculation of the extrapolar stratospheric ozone layer in coupled general circulation models (GCMs). In contrast to the widely used prescribed ozone, the SWIFT ozone layer interacts with the model dynamics and can respond to atmospheric variability or climatological trends.The Extrapolar SWIFT model employs a repro-modelling approach, in which algebraic functions are used to approximate the numerical output of a full stratospheric chemistry and transport model (ATLAS). The full model solves a coupled chemical differential equation system with 55 initial and boundary conditions (mixing ratio of various chemical species and atmospheric parameters). Hence the rate of change of ozone over 24 h is a function of 55 variables. Using covariances between these variables, we can find linear combinations in order to reduce the parameter space to the following nine basic variables: latitude, pressure altitude, temperature, overhead ozone column and the mixing ratio of ozone and of the ozone-depleting families (Cly, Bry, NOy and HOy). We will show that these nine variables are sufficient to characterize the rate of change of ozone. An automated procedure fits a polynomial function of fourth degree to the rate of change of ozone obtained from several simulations with the ATLAS model. One polynomial function is determined per month, which yields the rate of change of ozone over 24 h. A key aspect for the robustness of the Extrapolar SWIFT model is to include a wide range of stratospheric variability in the numerical output of the ATLAS model, also covering atmospheric states that will occur in a future climate (e.g. temperature and meridional circulation changes or reduction of stratospheric chlorine loading).For validation purposes, the Extrapolar SWIFT model has been integrated into the ATLAS model, replacing the full stratospheric chemistry scheme. Simulations with SWIFT in ATLAS have proven that the systematic error is small and does not accumulate during the course of a simulation. In the context of a 10-year simulation, the ozone layer simulated by SWIFT shows a stable annual cycle, with inter-annual variations comparable to the ATLAS model. The application of Extrapolar SWIFT requires the evaluation of polynomial functions with 30-100 terms. Computers can currently calculate such polynomial functions at thousands of model grid points in seconds. SWIFT provides the desired numerical efficiency and computes the ozone layer 104 times faster than the chemistry scheme in the ATLAS CTM.

On Relations Between the Ozonosphere and the General Atmospheric Circulation in Tropics

NASA Astrophysics Data System (ADS)

Kuznetsov, G. I.; Kramarova, N. A.

2006-05-01

The main features of temporal and spatial ozone distribution over tropics and their relations with peculiarities of the general atmospheric circulation are obtained using the total ozone data for the tropical region (Ozone Data for the World and TOMS (version 8)). Among the factors influencing ozone regime in tropics the properties of the region, like intertropical convergence zone and a structure of tropical tropopause, and processes such as stratosphere-troposphere exchange, migration of ozone equator, Quasi Biennial Oscillation are analyzed. To investigate the long term variability of tropical ozone detrended and de-seasonalized fields of TOMS observations are analyzed by means of EOF method. The first four EOFs explain about 75% of residual total ozone variability in tropical region. Spatial patterns of EOFs and corresponding time coefficients are closely connected with the Quasi-Biennial Oscillation (EOF-1), the 11-years Solar Cycle (EOF-2), the QBO-annual beat (EOF-3) and with the South Oscillation (EOF-4) correspondingly. The detailed analyses of temporal and spatial distribution of ozone EOF patterns reveals a distinct change of ozone fields to the both sides of equator at 10-15 latitude as well as at the zones of tropical tropopause break. A time delay of ozone QBO phase is observed while moving towards higher latitudes. Some features of the tropical ozone regime manifest themselves in the peculiarities of Antarctic Ozone Anomalies. A time variability of ozone QBO passes three months ahead of the Singapore 30 mbar zonal wind. Obtained relations let us to construct a linear regression model based on EOF decomposition to estimate total ozone monthly means over tropics. This model is successfully applied to predict 30 mbar zonal wind in dependence on tropical ozone behavior.

Recent advances in satellite observations of solar variability and global atmospheric ozone

NASA Technical Reports Server (NTRS)

Heath, D. F.

1974-01-01

A description is given of the temporal behavior of the sun as an ultraviolet variable star in relation to daily zonal means of atmospheric ozone from the total amount to that above the 10-mb and 4-mb pressure levels. A significant correlation has been observed between enhancements in the ultraviolet solar irradiances and terrestrial passages of the solar magnetic field sector boundary structure. However, it has not yet been possible to separate solar from the dynamical effects on the variability in the zonal means of ozone. Attention is given to global changes in ozone which have been derived from the satellite observations in terms of season, solar variability, and major stratospheric disturbances such as stratospheric warmings.

Impact of climate variability on tropospheric ozone.

PubMed

Grewe, Volker

2007-03-01

A simulation with the climate-chemistry model (CCM) E39/C is presented, which covers both the troposphere and stratosphere dynamics and chemistry during the period 1960 to 1999. Although the CCM, by its nature, is not exactly representing observed day-by-day meteorology, there is an overall model's tendency to correctly reproduce the variability pattern due to an inclusion of realistic external forcings, like observed sea surface temperatures (e.g. El Niño), major volcanic eruption, solar cycle, concentrations of greenhouse gases, and Quasi-Biennial Oscillation. Additionally, climate-chemistry interactions are included, like the impact of ozone, methane, and other species on radiation and dynamics, and the impact of dynamics on emissions (lightning). However, a number of important feedbacks are not yet included (e.g. feedbacks related to biogenic emissions and emissions due to biomass burning). The results show a good representation of the evolution of the stratospheric ozone layer, including the ozone hole, which plays an important role for the simulation of natural variability of tropospheric ozone. Anthropogenic NO(x) emissions are included with a step-wise linear trend for each sector, but no interannual variability is included. The application of a number of diagnostics (e.g. marked ozone tracers) allows the separation of the impact of various processes/emissions on tropospheric ozone and shows that the simulated Northern Hemisphere tropospheric ozone budget is not only dominated by nitrogen oxide emissions and other ozone pre-cursors, but also by changes of the stratospheric ozone budget and its flux into the troposphere, which tends to reduce the simulated positive trend in tropospheric ozone due to emissions from industry and traffic during the late 80s and early 90s. For tropical regions the variability in ozone is dominated by variability in lightning (related to ENSO) and stratosphere-troposphere exchange (related to Northern Hemisphere Stratospheric dynamics and solar activity). Since tropospheric background chemistry is regarded only, the results are quantitatively limited with respect to derived trends. However, the main results are regarded to be robust. Although the horizontal resolution is rather coarse in comparison to regional models, such kind of simulations provide useful and necessary information on the impact of large-scale processes and inter-annual/decadal variations on regional air quality.

Multi-Model Assessment of the Factors Driving Stratospheric Ozone Evolution Over the 21st Century

NASA Technical Reports Server (NTRS)

Oman, L. D.; Plummer, D. A.; Waugh, D. W.; Austin, J.; Scinocca, J.; Douglass, A. R.; Salawitch, R. J.; Canty, T.; Akiyoshi, H.; Bekki, S.;

The Response of Lower Atmospheric Ozone to ENSO in Aura Measurements and a Chemistry-Climate Simulation

NASA Technical Reports Server (NTRS)

Oman, L. D.; Douglass, A. R.; Ziemke, J. R.; Rodriquez, J. M.; Waugh, D. W.; Nielsen, J. E.

2012-01-01

The El Nino-Southern Oscillation (ENSO) is the dominant mode of tropical variability on interannual time scales. ENSO appears to extend its influence into the chemical composition of the tropical troposphere. Recent work has revealed an ENSO-induced wave-1 anomaly in observed tropical tropospheric column ozone. This results in a dipole over the western and eastern tropical Pacific, whereby differencing the two regions produces an ozone anomaly with an extremely high correlation to the Nino 3.4 Index. We have successfully reproduced this feature using the Goddard Earth Observing System Version 5 (GEOS-5) general circulation model coupled to a comprehensive stratospheric and tropospheric chemical mechanism forced with observed sea surface temperatures over the past 25 years. An examination of the modeled ozone field reveals the vertical contributions of tropospheric ozone to the column over the western and eastern Pacific region. We will show composition sensitivity in observations from NASA s Aura satellite Microwave Limb Sounder (MLS) and the Tropospheric Emissions Spectrometer (TES) and a simulation to provide insight into the vertical structure of these ENSO-induced ozone changes. The ozone changes due to the Quasi-Biennial Oscillation (QBO) in the extra-polar upper troposphere and lower stratosphere in MLS measurements will also be discussed.

Variability of total ozone at Arosa, Switzerland, since 1931 related to atmospheric circulation indices

NASA Astrophysics Data System (ADS)

Brönnimann, S.; Luterbacher, J.; Schmutz, C.; Wanner, H.; Staehelin, J.

2000-08-01

Atmospheric circulation determines to a considerable extent the variability of lower stratospheric ozone and can modulate its long-term trends in Europe and the North Atlantic Region. Due to dynamical stratosphere-troposphere coupling, important features of the variability of the surface pressure field are reflected in the long-term total ozone record from Arosa, Switzerland. Significant (p<0.01) correlations between total ozone and different atmospheric circulation indices (NAOI, AOI, EU1, EU2) are found in all months except for April, June, July, and November for the period 1931 to 1997. An analysis of geopotential heights for the period 1958 to 1997 shows that these circulation anomaly patterns have upper tropospheric features over the North Atlantic-European sector that are consistent with a dynamical influence on total ozone.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newchurch, M.

The objectives of this research were to: (1) examine empirically the aerosol effect on Umkehr ozone profiles using SAGE II aerosol and ozone data; (2) examine theoretically the aerosol effect on Umkehr ozone profiles; (3) examine the differences between SAGE II ozone profiles and both old- and new-format Umkehr ozone profiles for ozone-trend information; (4) reexamine SAGE I-Umkehr ozone differences with the most recent version of SAGE I data; and (5) contribute to the SAGE II science team.

An investigation into the causes of stratospheric ozone loss in the southern Australasian region

NASA Astrophysics Data System (ADS)

Lehmann, P.; Karoly, D. J.; Newmann, P. A.; Clarkson, T. S.; Matthews, W. A.

1992-07-01

Measurements of total ozone at Macquarie Island (55 deg S, 159 deg E) reveal statistically significant reductions of approximately twelve percent during July to September when comparing the mean levels for 1987-90 with those in the seventies. In order to investigate the possibility that these ozone changes may not be a result of dynamic variability of the stratosphere, a simple linear model of ozone was created from statistical analysis of tropopause height and isentropic transient eddy heat flux, which were assumed representative of the dominant dynamic influences. Comparison of measured and modeled ozone indicates that the recent downward trend in ozone at Macquarie Island is not related to stratospheric dynamic variability and therefore suggests another mechanism, possibly changes in photochemical destruction of ozone.

Exposure to medium and high ambient levels of ozone causes adverse systemic inflammatory and cardiac autonomic effects

PubMed Central

Wong, Hofer; Donde, Aneesh; Frelinger, Jessica; Dalton, Sarah; Ching, Wendy; Power, Karron; Balmes, John R.

2015-01-01

Epidemiological evidence suggests that exposure to ozone increases cardiovascular morbidity. However, the specific biological mechanisms mediating ozone-associated cardiovascular effects are unknown. To determine whether short-term exposure to ambient levels of ozone causes changes in biomarkers of cardiovascular disease including heart rate variability (HRV), systemic inflammation, and coagulability, 26 subjects were exposed to 0, 100, and 200 ppb ozone in random order for 4 h with intermittent exercise. HRV was measured and blood samples were obtained immediately before (0 h), immediately after (4 h), and 20 h after (24 h) each exposure. Bronchoscopy with bronchoalveolar lavage (BAL) was performed 20 h after exposure. Regression modeling was used to examine dose-response trends between the endpoints and ozone exposure. Inhalation of ozone induced dose-dependent adverse changes in the frequency domains of HRV across exposures consistent with increased sympathetic tone [increase of (parameter estimate ± SE) 0.4 ± 0.2 and 0.3 ± 0.1 in low- to high-frequency domain HRV ratio per 100 ppb increase in ozone at 4 h and 24 h, respectively (P = 0.02 and P = 0.01)] and a dose-dependent increase in serum C-reactive protein (CRP) across exposures at 24 h [increase of 0.61 ± 0.24 mg/l in CRP per 100 ppb increase in ozone (P = 0.01)]. Changes in HRV and CRP did not correlate with ozone-induced local lung inflammatory responses (BAL granulocytes, IL-6, or IL-8), but changes in HRV and CRP were associated with each other after adjustment for age and ozone level. Inhalation of ozone causes adverse systemic inflammatory and cardiac autonomic effects that may contribute to the cardiovascular mortality associated with short-term exposure. PMID:25862833

Blue wild-rye grass competition increases the effect of ozone on ponderosa pine seedlings.

PubMed

Andersen, C P; Hogsett, W E; Plocher, M; Rodecap, K; Lee, E H

2001-03-01

Individual ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings were grown in mesocosms with three densities of blue wild-rye grass (Elymus glaucus Buckl.) (equivalent to 0, 32 or 88 plants m-2) to determine if the presence of a natural competitor alters the response of ponderosa pine seedlings to ozone. After 3 years of ozone exposure, grass presence reduced total ponderosa pine dry mass by nearly 50%, whereas ozone alone had no significant effect on ponderosa pine growth. The combination of ozone and grass further reduced needle, stem and branch dry mass significantly below that induced by grass competition alone. Root:shoot ratios increased in response to the combined grass and ozone treatments. Grass competition significantly reduced soluble sugar concentrations in all ponderosa pine tissue components examined. Starch concentrations were highly variable but did not differ significantly between treatments. Ozone significantly reduced soluble sugar concentrations in fine roots and stems. In the absence of grass, ozone-treated seedlings tended to have higher tissue N concentrations than controls. In the presence of grass, ozone-treated seedlings had lower N concentrations than controls, resulting in a significant interaction between these two stresses in 1- and 2-year-old needles. Needle C:N ratios decreased in response to grass competition, as a result of increased N concentration and no change in C concentration. The opposite response was observed in ozone-treated seedlings as a result of decreased N concentrations, indicating that ozone-treated seedlings were unable to take up or retain as much nitrogen when grown in the presence of grass. We conclude that ponderosa pine seedlings are more susceptible to ozone when grown in competition with blue wild-rye grass.

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.;

Short-term effects of multiple ozone metrics on daily mortality in a megacity of China.

PubMed

Li, Tiantian; Yan, Meilin; Ma, Wenjun; Ban, Jie; Liu, Tao; Lin, Hualiang; Liu, Zhaorong

2015-06-01

Epidemiological studies have widely demonstrated association between ambient ozone and mortality, though controversy remains, and most of them only use a certain metric to assess ozone levels. However, in China, few studies have investigated the acute effects of ambient ozone, and rare studies have compared health effects of multiple daily metrics of ozone. The present analysis aimed to explore variability of estimated health effects by using multiple temporal ozone metrics. Six metrics of ozone, 1-h maximum, maximum 8-h average, 24-h average, daytime average, nighttime average, and commute average, were used in a time-series study to investigate acute mortality associated with ambient ozone pollution in Guangzhou, China, using 3 years of daily data (2006-2008). We used generalized linear models with Poisson regression incorporating natural spline functions to analyze the mortality, ozone, and covariate data. We also examined the association by season. Daily 1- and 8-h maximum, 24-h average, and daytime average concentrations yielded statistically significant associations with mortality. An interquartile range (IQR) of O3 metric increase of each ozone metric (lag 2) corresponds to 2.92 % (95 % confidence interval (CI) 0.24 to 5.66), 3.60 % (95 % CI, 0.92 to 8.49), 3.03 % (95 % CI, 0.57 to 15.8), and 3.31 % (95 % CI, 0.69 to 10.4) increase in daily non-accidental mortality, respectively. Nighttime and commute metrics were weakly associated with increased mortality rate. The associations between ozone and mortality appeared to be more evident during cool season than in the warm season. Results were robust to adjustment for co-pollutants, weather, and time trend. In conclusion, these results indicated that ozone, as a widespread pollutant, adversely affects mortality in Guangzhou.

Southern Hemisphere Additional Ozonesondes (SHADOZ) ozone climatology (2005-2009): Tropospheric and tropical tropopause layer (TTL) profiles with comparisons to OMI-based ozone products

NASA Astrophysics Data System (ADS)

Thompson, Anne M.; Miller, Sonya K.; Tilmes, Simone; Kollonige, Debra W.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Johnson, Bryan J.; Fujiwara, Masatomo; Schmidlin, F. J.; Coetzee, G. J. R.; Komala, Ninong; Maata, Matakite; Bt Mohamad, Maznorizan; Nguyo, J.; Mutai, C.; Ogino, S.-Y.; da Silva, F. Raimundo; Leme, N. M. Paes; Posny, Francoise; Scheele, Rinus; Selkirk, Henry B.; Shiotani, Masato; Stübi, René; Levrat, Gilbert; Calpini, Bertrand; Thouret, ValéRie; Tsuruta, Haruo; Canossa, Jessica Valverde; VöMel, Holger; Yonemura, S.; Diaz, Jorge AndréS.; Tan Thanh, Nguyen T.; Thuy Ha, Hoang T.

2012-12-01

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 Cristóbal, 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 EP/TOMS comparisons (1998-2004; Earth-Probe/Total 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 OMI/MLS) 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.

Assessment of ozone variations and meteorological effects in an urban area in the Mediterranean Coast.

PubMed

Dueñas, C; Fernández, M C; Cañete, S; Carretero, J; Liger, E

2002-11-01

Ozone concentrations are valuable indicators of possible health and environmental impacts. However, they are also used to monitor changes and trends in the sources of both ozone and its precursors. For this purpose, the influence of meteorological variables is a confusing factor. This study presents an analysis of a year of ozone concentrations measured in a coastal Spanish city. Firstly, the aim of this study was to perceive the daily, monthly and seasonal variation patterns of ozone concentrations. Diurnal cycles are presented by season and the fit of the data to a normal distribution is tested. In order to assess ozone behaviour under temperate weather conditions, local meteorological variables (wind direction and speed, temperature, relative humidity, pressure and rainfall) were monitored together with ozone concentrations. The main relationships we could observe in these analyses were then used to obtain a regression equation linking diurnal ozone concentrations in summer with meteorological parameters.

Contributions of regional and intercontinental transport to surface ozone in the Tokyo area

NASA Astrophysics Data System (ADS)

Yoshitomi, M.; Wild, O.; Akimoto, H.

2011-08-01

Japan lies downwind of the Asian continent and for much of the year air quality is directly influenced by emissions of ozone precursors over these heavily-populated and rapidly-industrializing regions. This study examines the extent to which oxidant transport from regional and distant anthropogenic sources influences air quality in Japan in springtime, when these contributions are largest. We find that European and North American contributions to surface ozone over Japan in spring are persistent, averaging 3.5±1.1 ppb and 2.8±0.5 ppb respectively, and are greatest in cold continental outflow conditions following the passage of cold fronts. Contributions from China are larger, 4.0±2.8 ppb, and more variable, as expected for a closer source region, and are generally highest near cold fronts preceding the influence of more distant sources. The stratosphere provides a varying but ever-present background of ozone of about 11.2±2.5 ppb during spring. Local sources over Japan and Korea have a relatively small impact on mean ozone, 2.4±7.6 ppb, but this masks a strong diurnal signal, and local sources clearly dominate during episodes of high daytime ozone. By examining the meteorological mechanisms that favour transport from different source regions, we demonstrate that while maximum foreign influence generally does not occur at the same time as the greatest buildup of oxidants from local sources, it retains a significant influence under these conditions. It is thus clear that while meteorological boundaries provide some protection from foreign influence during oxidant outbreaks in Tokyo, these distant sources still make a substantial contribution to exceedance of the Japanese ozone air quality standard in springtime.

Contributions of regional and intercontinental transport to surface ozone in Tokyo

NASA Astrophysics Data System (ADS)

Yoshitomi, M.; Wild, O.; Akimoto, H.

2011-04-01

Japan lies downwind of the Asian continent and for much of the year air quality is directly influenced by emissions of ozone precursors over these heavily-populated and rapidly-industrializing regions. This study examines the extent to which oxidant transport from regional and distant anthropogenic sources influences air quality in Japan in springtime, when these contributions are largest. We find that European and North American contributions to surface ozone over Japan in spring are persistent, averaging 3.5±1.1 ppb and 2.8±0.5 ppb respectively, and are greatest in cold continental outflow conditions following the passage of cold fronts. Contributions from China are larger, 4.0±2.8 ppb, and more variable, as expected for a closer source region, and are generally highest near cold fronts preceding the influence of more distant sources. The stratosphere provides a varying but ever-present background of ozone of about 11.2±2.5 ppb during spring. Local sources over Japan and Korea have a relatively small impact on mean ozone, 2.4±7.6 ppb, but this masks a strong diurnal signal, and local sources clearly dominate during episodes of high daytime ozone. By examining the meteorological mechanisms that favour transport from different source regions, we demonstrate that while maximum foreign influence generally does not occur at the same time as the greatest buildup of oxidants from local sources, it retains a significant influence under these conditions. It is thus clear that while meteorological boundaries provide some protection from foreign influence during oxidant outbreaks in Tokyo, these distant sources still make a substantial contribution to exceedance of the Japanese ozone air quality standard in springtime.

Use of satellite data and modeling to assess the influence of stratospheric processes on the troposphere

NASA Astrophysics Data System (ADS)

Nathan, Terrence

1991-09-01

Over the past forty years, numerous linear stability studies have been performed in order to explain the origin and structure of observed waves in the atmosphere. Of these studies, only a small fraction have considered the stability of time-dependent, zonally varying flow or the influence of radiative-photochemical feedbacks on the stability of zonally uniform flow. The stability of such flows is described, and these flows may yield important information concerning the origin, structure, and transient time scales of free waves in the atmosphere. During the period 1990 to 1991, a beta-plane model that couples radiative transfer, ozone advection, and ozone photochemistry with the quasigeostrophic dynamical circulation was developed in order to study the diabatic effects of Newtonian cooling and ozone-dynamics interaction on the linear stability of free planetary waves in the atmosphere. The stability of a basic state consisting of a westward-moving wave and a zonal mean jet was examined using a linearized, nondivergent barotropic model on sphere. The sensitivity of the stability of the flow to the strength and structure of the zonal jet was emphasized. The current research is focused on the following problems: (1) examination of the finite amplitude interactions among radiation, ozone, and dynamics; and (2) examination of the role of seasonal forcing in short-term climate variability. The plans for next year are presented.

Impacts of Interannual Variability in Biogenic VOC Emissions near Transitional Ozone Production Regimes

NASA Astrophysics Data System (ADS)

Geddes, J.

2017-12-01

Due to successful NOx emission controls, summertime ozone production chemistry in urban areas across North America is transitioning from VOC-limited to increasingly NOx-limited. In some regions where ozone production sensitivity is in transition, interannual variability in surrounding biogenic VOC emissions could drive fluctuations in the prevailing chemical regime and modify the impact of anthropogenic emission changes. I use satellite observations of HCHO and NO2 column density, along with a long-term simulation of atmospheric chemistry, to investigate the impact of interannual variability in biogenic isoprene sources near large metro areas. Peak emissions of isoprene in the model can vary by up to 20-60% in any given year compared to the long term mean, and this variability drives the majority of the variability in simulated local HCHO:NO2 ratios (a common proxy for ozone production sensitivity). The satellite observations confirm increasingly NOx-limited chemical regimes with large interannual variability. In several instances, the model and satellite observations suggest that variability in biogenic isoprene emissions could shift summertime ozone production from generally VOC- to generally NOx- sensitive (or vice versa). This would have implications for predicting the air quality impacts of anthropogenic emission changes in any given year, and suggests that drivers of biogenic emissions need to be well understood.

Interrelation of changes in the total content of ozone in the northern hemisphere with the velocity of the stratosphere circumpolar vortex

NASA Astrophysics Data System (ADS)

Kolyada, Maria N.; Kashkin, Valentin B.

2004-12-01

Considering the high significance of the ozone for preservation and maintenance of the biosphere and the temperature balance of the atmosphere the investigation of the ozone layer is a very important part of the investigation of the planet"s atmosphere. In this work results of investigations of TOC variability in the Northern Hemisphere and the influence of variability of the circumpolar vortex rotation velocity on the ozone layer are presented. Mean values of total ozone concentration in the Northern Hemisphere (by satellite data) and rotation velocities of the circumpolar vortex are calculated for each month from February to April during 1998-2004. Also in this work the mechanism of the influence of the natural factors on TOC variability solar activity during the spring is suggested.

Variability of winter and summer surface ozone in Mexico City on the intraseasonal timescale

NASA Astrophysics Data System (ADS)

Barrett, Bradford S.; Raga, Graciela B.

2016-12-01

Surface ozone concentrations in Mexico City frequently exceed the Mexican standard and have proven difficult to forecast due to changes in meteorological conditions at its tropical location. The Madden-Julian Oscillation (MJO) is largely responsible for intraseasonal variability in the tropics. Circulation patterns in the lower and upper troposphere and precipitation are associated with the oscillation as it progresses eastward around the planet. It is typically described by phases (labeled 1 through 8), which correspond to the broad longitudinal location of the active component of the oscillation with enhanced precipitation. In this study we evaluate the intraseasonal variability of winter and summer surface ozone concentrations in Mexico City, which was investigated over the period 1986-2014 to determine if there is a modulation by the MJO that would aid in the forecast of high-pollution episodes. Over 1 000 000 hourly observations of surface ozone from five stations around the metropolitan area were standardized and then binned by active phase of the MJO, with phase determined using the real-time multivariate MJO index. Highest winter ozone concentrations were found in Mexico City on days when the MJO was active and in phase 2 (over the Indian Ocean), and highest summer ozone concentrations were found on days when the MJO was active and in phase 6 (over the western Pacific Ocean). Lowest winter ozone concentrations were found during active MJO phase 8 (over the eastern Pacific Ocean), and lowest summer ozone concentrations were found during active MJO phase 1 (over the Atlantic Ocean). Anomalies of reanalysis-based cloud cover and UV-B radiation supported the observed variability in surface ozone in both summer and winter: MJO phases with highest ozone concentration had largest positive UV-B radiation anomalies and lowest cloud-cover fraction, while phases with lowest ozone concentration had largest negative UV-B radiation anomalies and highest cloud-cover fraction. Furthermore, geopotential height anomalies at 250 hPa favoring reduced cloudiness, and thus elevated surface ozone, were found in both seasons during MJO phases with above-normal ozone concentrations. Similar height anomalies at 250 hPa favoring enhanced cloudiness, and thus reduced surface ozone, were found in both seasons during MJO phases with below-normal ozone concentrations. These anomalies confirm a physical pathway for MJO modulation of surface ozone via modulation of the upper troposphere.

A Statistical Modeling Framework for Projecting Future Ambient Ozone and its Health Impact due to Climate Change

PubMed Central

Chang, Howard H.; Hao, Hua; Sarnat, Stefanie Ebelt

2014-01-01

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% to 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. PMID:24764746

Comparison and covalidation of ozone anomalies and variability observed in SBUV(/2) and Umkehr northern midlatitude ozone profile estimates

NASA Astrophysics Data System (ADS)

Petropavlovskikh, I.; Ahn, Changwoo; Bhartia, P. K.; Flynn, L. E.

2005-03-01

This analysis presents comparisons of upper-stratosphere ozone information observed by two independent systems: the Solar Backscatter UltraViolet (SBUV and SBUV/2) satellite instruments, and ground-based Dobson spectrophotometers. Both the new SBUV Version 8 and the new UMK04 profile retrieval algorithms are optimized for studying long-term variability and trends in ozone. Trend analyses of the ozone time series from the SBUV(/2) data set are complex because of the multiple instruments involved, changes in the instruments' geo-location, and short periods of overlaps for inter-calibrations among different instruments. Three northern middle latitudes Dobson ground stations (Arosa, Boulder, and Tateno) are used in this analysis to validate the trend quality of the combined 25-year SBUV/2 time series, 1979 to 2003. Generally, differences between the satellite and ground-based data do not suggest any significant time-dependent shifts or trends. The shared features confirm the value of these data sets for studies of ozone variability.

Analysis of a 7 year tropospheric ozone vertical distribution at the Observatoire de Haute Provence

NASA Technical Reports Server (NTRS)

Beekmann, Matthias; Ancellet, Gerard; Megie, Gerard

1994-01-01

A seven year (1984-90) climatology of tropospheric vertical ozone soundings, performed by electrochemical sondes at the OHP (44 deg N, 6 deg E, 700 m ASL) in Southern France, is presented. Its seasonal variation shows a broad spring/summer maximum in the troposphere. The contribution of photochemical ozone production and transport from the stratosphere to this seasonal variation are studied by a correlative analysis of ozone concentrations and meteorological variables, with emphasis on potential vorticity. This analysis shows the impact of dynamical and photochemical processes on the spatial and temporal ozone variability. In particular, a positive correlation (r = 04.0, significance greater than 99.9 percent) of ozone with potential vorticity is observed in the middle troposphere, reflecting the impact of stratosphere-troposphere exchange on the vertical ozone distribution.

Insights into Tropical Tropospheric Ozone from Satellite and Sonde Data

NASA Technical Reports Server (NTRS)

Thompson, Anne M.

2003-01-01

The first climatological overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropical and subtropics is based on ozone sounding data from 10 sites comprising the Southern Hemisphere Additional OZonesondes (SHADOZ) network. Observations were made over: Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. The data reside at: http://code916.gsfc.nasa.gov/Data_services/shadoz. SHADOZ ozone time-series and profiles give a perspective on tropical total, stratospheric and tropospheric ozone. Prominent features are highly variable tropospheric ozone and a zonal wave-one pattern in total (and tropospheric) column ozone. Dynamical and chemical influences appear to be of comparable magnitude though model studies are needed to quantify this. In addition to leading the SHADOZ network, we have been producing near-real tropical tropospheric ozone ('TTO') data from the Total Ozone Mapping Spectrometer (TOMS) since 1997 with Prof. Hudson and students at the University of Maryland: http://metosrv2.umd.edu/tropo. Further perspective on the complexity of tropospheric ozone variability is shown using satellite observations.

Analysis and validation of ozone variability observed by lidar during the ESCOMPTE-2001 campaign

NASA Astrophysics Data System (ADS)

Ancellet, G.; Ravetta, F.

2005-03-01

An ozone lidar was successfully operated as a ground-based instrument during the ESCOMPTE experiment in June/July 2001. Ozone profiles were measured between 0.5 and 5 km. Moreover, simultaneous measurements of the lidar scattering ratio (SR) at 316 nm diagnosed the diurnal evolution of the PBL top. Comparison of this data set with in-situ measurements by ultralight aircraft (ULM) and balloon soundings supports the existence of well-defined layers over the whole altitude range. Differences between measurements techniques are not due to instrumental inaccuracies but point towards the existence of ozone plumes with sharp horizontal gradients. This is indeed supported by aircraft horizontal cross-section available twice a day at two different levels in the planetary boundary layer (PBL) and the free troposphere. Analysis of the ozone data set has shown a good correlation between surface meteorological conditions, surface ozone measurements and lidar ozone profiles in the PBL. Observed ozone maxima or minima are linked either to sea breeze circulation bringing polluted air masses over the lidar or synoptic flows bringing air with background O 3 values into the region. The observed variability of the ozone field is very large over the whole altitude range. Although it is the result of local temporal variability and advection of spatial inhomogenities, the latter proved to be an important contribution.

Linking North American Summer Ozone Pollution Episodes to Subseasonal Atmospheric Variability

NASA Astrophysics Data System (ADS)

White, E. C.; Watt-Meyer, O.; Kushner, P. J.; Jones, D. B. A.

2017-12-01

Ozone concentrations in the planetary boundary layer (PBL) are positively correlated with surface air temperature due to shared influences including incident solar radiation and PBL stagnancy, as well as the temperature-sensitive emission of ozone precursor compounds. While previous studies have linked heat waves in North America to modes of subseasonal atmospheric variability, such analyses have not been applied to summertime ozone pollution episodes. This study investigates a possible link between subseasonal atmospheric variability in reanalysis data and summertime ozone pollution episodes identified in almost thirty years of in-situ measurements from the Air Quality System (AQS) network in the United States. AQS stations are grouped into regions likely to experience simultaneous extreme ozone concentrations using statistical clustering methods. Composite meteorological patterns are calculated for ozone episodes in each of these regions. The same analysis is applied to heat waves identified in AQS temperature records for comparison. Local meteorological features during typical ozone episodes include extreme temperatures and reduced cloud cover related to anomalous synoptic-scale anticyclonic circulation aloft. These anticyclonic anomalies are typically embedded in wave trains extending from the North Pacific to North Atlantic. Spectral analysis of these wave trains reveals that low-frequency standing waves play a prominent role. These long-lived circulation patterns may provide a means to increase air quality prediction lead-times and to estimate the frequency of ozone pollution episodes under climate change.

Modeling and Observations of the Response of Tropical Tropospheric Ozone to ENSO

NASA Technical Reports Server (NTRS)

Oman, L. D.; Douglass, A. R.; Ziemke, J. R.; Waugh, D. W.; Lang, C.; Rodriquez, J. M.; Nielsen, J. E.

2012-01-01

The El Nino-Southern Oscillation (ENSO) is the dominant mode of tropical variability on interannual time scales. ENSO appears to extend its influence into the chemical composition of the tropical troposphere, Recent results have revealed an ENSO induced wave-1 anomaly in observed tropical tropospheric column ozone, This results in a dipole over the western and eastern tropical Pacific, whereby differencing the two regions produces an ozone anomaly with an extremely high correlation to the Nino 3.4 Index. We have successfully reproduced this result using the Goddard Earth Observing System Version 5 (GEOS-5) general circulation model coupled to a comprehensive stratospheric and tropospheric chemical mechanism forced with observed sea surface temperatures over the past 25 years, An examination of the modeled ozone field reveals the vertical contributions of tropospheric ozone to the column over the western and eastern Pacific region, We will show targeted comparisons with SHADOZ ozonesondes over these regions to provide insight into the vertical structure. Also, comparisons with NASA's Aura satellite Microwave Limb Sounder (MLS) and Tropospheric Emissions Spectrometer (TES) instruments and other appropriate data sets will be shown. In addition, the water vapor response to ENSO will be compared to help illuminate its role relative to dynamics in impacting ozone concentrations. These results indicate that the tropospheric ozone response to ENSO is potentially a very useful chemistry-climate diagnostic and should be considered in future modeling assessments.

Spatial clustering and meteorological drivers of summer ozone in Europe

NASA Astrophysics Data System (ADS)

Carro-Calvo, Leopoldo; Ordóñez, Carlos; García-Herrera, Ricardo; Schnell, Jordan L.

2017-04-01

We present a regionalization of summer near-surface ozone (O3) in Europe. For this purpose we apply a K-means algorithm on a gridded MDA8 O3 (maximum daily average 8-h ozone) dataset covering a European domain [15° W - 30° E, 35°-70° N] at 1° x 1° horizontal resolution for the 1998-2012 period. This dataset was compiled by merging observations from the European Monitoring and Evaluation Programme (EMEP) and the European Environment Agency's air quality database (AirBase). The K-means method allows identifying sets of different regions where the O3 concentrations present coherent spatiotemporal patterns and are thus expected to be driven by similar meteorological factors. After some testing, 9 regions were selected: the British Isles, North-Central Europe, Northern Scandinavia, the Baltic countries, the Iberian Peninsula, Western Europe, South-Central Europe, Eastern Europe and the Balkans. For each region we examine the synoptic situations associated with elevated ozone extremes (days exceeding the 95th percentile of the summer MDA8 O3 distribution). Our analyses reveal that there are basically two different kinds of regions in Europe: (a) those in the centre and south of the continent where ozone extremes are associated with elevated temperature within the same region and (b) those in northern Europe where ozone extremes are driven by southerly advection of air masses from warmer, more polluted areas. Even when the observed patterns were initially identified only for days registering high O3 extremes, all summer days can be projected on such patterns to identify the main modes of meteorological variability of O3. We have found that such modes are partly responsible for the day-to-day variability in the O3 concentrations and can explain a relatively large fraction (from 44 to 88 %, depending on the region) of the interannual variability of summer mean MDA8 O3 during the period of analysis. On the other hand, some major teleconnection patterns have been tested but do not seem to exert a large impact on the variability of surface O3 over most regions. The identification of these independent regions where surface ozone presents a coherent behaviour and responds similarly to specific meteorological modes of variability has multiple applications. For instance, the performance of chemical transport models (CTMs) and chemistry-climate models (CCMs) can be separately assessed over such regions to identify areas where they present large biases that need to be corrected. Our results can also be used to test the models' sensitivity to the day-to-day changing meteorology and to climate change over specific regions.

Decadal trends in tropospheric ozone over East Asian Pacific rim during 1998-2007: Implications for emerging Asian emissions impacts and comparison to European and North American records (Invited)

NASA Astrophysics Data System (ADS)

Tanimoto, H.; Ohara, T.; Uno, I.

2010-12-01

We examine springtime ozone trends at nine remote locations in East Asian Pacific rim during the last decade (1998-2007). The observed decadal ozone trends are relatively small at surface sites but are substantially larger at a mountainous site. The level and increasing rate of ozone at the mountainous site are both higher than those observed at background sites in Europe and North America. We use a regional chemistry-transport model to explore the observed changes and how changes in Asian anthropogenic emissions have contributed to the observed increasing trends. The model with yearly-dependent regional emissions successfully reproduces the levels, variability, and interannual variations of ozone at all the surface sites. It predicts increasing trends at the mountainous site, suggesting that increasing Asian anthropogenic emissions account for about half the observed increase. However, the discrepancy between the observation and model results after 2003 (the time of largest emission increase) suggests significant underestimation of the actual growth of the Asian anthropogenic emissions and/or incompleteness in the modeling of pollution export from continental Asia. These findings imply that improving emissions inventory and transport scheme is needed to better understand rapidly evolving tropospheric ozone in East Asia and its potential climatic and environmental impacts.

Regional Variability in Ozone in the Tropical and Subtropical Free Troposphere and Tropopause Transition Layer based on Aura-Era SHADOZ Data (2005-2009)

NASA Astrophysics Data System (ADS)

Miller, S. K.; Thompson, A. M.; Witte, J. C.; Balashov, N. V.; Kollonige, D. E.

2012-12-01

The more than 5000 sets of ozone and P-T-U profiles provided for the tropics and subtropics by the Southern Hemisphere Additional Ozonesondes (SHADOZ) since 1998 have provided a wealth of insights into convective and mixing processes, especially in the upper troposphere through lower stratosphere. The observations have been used in evaluations of satellite ozone and chemical-transport and climate-chemistry models. Recently, we analyzed a climatology of ozone profiles based on the 2005-2009 SHADOZ data when 4 new stations joined the network (15 stations total), giving latitudinal coverage from 25S to 21N. We answer the following questions: How do ozone distributions at two new subtropical stations, Hanoi and Hilo in the northern hemisphere, compare to those at the southern subtropical stations, Irene and La Réunion? Are there better-defined regional classifications of tropospheric and tropopause transition layer (TTL) SHADOZ ozone profiles in the tropics, defined as within + 18 degrees latitude, than the Atlantic-Pacific differentiation identified in published studies with 1998-2004 SHADOZ data? Three distinct regions of the tropics are identified based on the criteria: ozone structure in the TTL; convective influence inferred from laminar identification (LID) of ozone and potential temperature; degree of pollution in the free troposphere (FT). These are: (1) western Pacific/eastern Indian Ocean; (2) equatorial Americas (San Cristóbal, Alajuela, Paramaribo); (3) Atlantic Ocean and Africa. In addition, we have re-examined potential trends in FT and TTL ozone at several SHADOZ stations for which data extend back to the early 1990s.

An Intercomparison of Tropospheric Ozone Retrievals Derived from Two Aura Instruments and Measurements in Western North America in 2006

NASA Technical Reports Server (NTRS)

Doughty, D. C.; Thompson, A. M.; Schoeberl, M. R.; Stajner, I.; Wargan, K.; Hui, W. C. J.

2011-01-01

Two recently developed methods for quantifying tropospheric ozone abundances based on Aura data, the Trajectory-enhanced Tropospheric Ozone Residual (TTOR) and an assimilation of Aura data into Goddard Earth Observing System Version 4 (ASM), are compared to ozone measurements from ozonesonde data collected in April-May 2006 during the INTEX Ozonesonde Network Study 2006 (IONS-06) campaign. Both techniques use Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) observations. Statistics on column ozone amounts for both products are presented. In general, the assimilation compares better to sonde integrated ozone to 200 hPa (28.6% difference for TTOR versus 2.7% difference for ASM), and both products are biased low. To better characterize the performance of ASM, ozone profiles based on the assimilation are compared to those from ozonesondes. We noted slight negative biases in the lower troposphere, and slight positive biases in the upper troposphere/lower stratosphere (UT/ LS), where we observed the greatest variability. Case studies were used to further understand ASM performance. We examine one case from 17 April 2006 at Bratt's Lake, Saskatchewan, where geopotential height gradients appear to be related to an underestimation in the ASM in the UT/LS region. A second case, from 21 April 2006 at Trinidad Head, California, is a situation where the overprediction of ozone in the UT/LS region does not appear to be due to current dynamic conditions but seems to be related to uncertainty in the flow pattern and large differences in MLS observations upstream.

The Validation of Version 8 Ozone Profiles: Is SBUV Ready for Prime Time?

NASA Technical Reports Server (NTRS)

McPeters, R. D.; Wellemeyer, C. G.; Ahn, C.

2004-01-01

Ozone profile data are now available from a series of BUV instruments - SBUV on Nimbus 7 and SBW/2 instruments on NOAA 9, NOAA 11, and NOAA 16. The data have been processed through the new version 8 algorithm, which is designed to be more accurate and, more importantly, to reduce the influence of the a priori on ozone trends. As a part of the version 8 reprocessing we have attempted to apply a consistent calibration to the individual instruments so that their data records can be used together in a time series analysis. Validation consists of examining not only the mean difference from external datasets (i.e trends) but also consistency in the interannual variability of the data. Here we validate the v8 BUV data through comparison with ECC sondes, lidar and microwave measurements, and with SAGE II and HALOE satellite data records. We find that individual profiles generally agree with external data sets within +/-10% between 30 hPa and 1 hPa (approx. 24 - 50 km) and frequently agree within +/-5%. The interannual variability of the BUV ozone time series agrees well with that of SAGE II . On the average, different B W instruments usually agree within +/-5% with each other, though the relative error increases near the ends of the Nimbus 7 and NOAA 16 data records as a result of instrument problems. The combined v8 BUV data sets cover the 1979-2003 time period giving daily global coverage of the ozone vertical distribution to better accuracy than has ever been possible before.

Air pollution and heart rate variability: effect modification by chronic lead exposure.

PubMed

Park, Sung Kyun; O'Neill, Marie S; Vokonas, Pantel S; Sparrow, David; Wright, Robert O; Coull, Brent; Nie, Huiling; Hu, Howard; Schwartz, Joel

2008-01-01

Outdoor air pollution and lead exposure can disturb cardiac autonomic function, but the effects of both these exposures together have not been studied. We examined whether higher cumulative lead exposures, as measured by bone lead, modified cross-sectional associations between air pollution and heart rate variability among 384 elderly men from the Normative Aging Study. We used linear regression, controlling for clinical, demographic, and environmental covariates. We found graded, significant reductions in both high-frequency and low-frequency powers of heart rate variability in relation to ozone and sulfate across the quartiles of tibia lead. Interquartile range increases in ozone and sulfate were associated respectively, with 38% decrease (95% confidence interval = -54.6% to -14.9%) and 22% decrease (-40.4% to 1.6%) in high frequency, and 38% decrease (-51.9% to -20.4%) and 12% decrease (-28.6% to 9.3%) in low frequency, in the highest quartile of tibia lead after controlling for potential confounders. We observed similar but weaker effect modification by tibia lead adjusted for education and cumulative traffic (residuals of the regression of tibia lead on education and cumulative traffic). Patella lead modified only the ozone effect on heart rate variability. People with long-term exposure to higher levels of lead may be more sensitive to cardiac autonomic dysfunction on high air pollution days. Efforts to understand how environmental exposures affect the health of an aging population should consider both current levels of pollution and history of lead exposure as susceptibility factors.

Atmospheric conditions and transport patterns associated with high and low summer ozone levels in the lower troposphere and the boundary layer over the eastern Mediterranean

NASA Astrophysics Data System (ADS)

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

2016-04-01

Vertical summertime ozone profiles measured in the period 1994-2008 in the framework of the MOZAIC project over the Eastern Mediterranean basin (especially over the Cairo and Tel-Aviv airports) were analysed, focusing at first in the lower troposphere (1.5-5 km). The vertical profiles collected during extreme days with very high or very low tropospheric ozone mixing ratios have been examined together with the average profiles of relative humidity, carbon monoxide, temperature gradient, wind speed and the corresponding composite maps of geopotential heights at 850 hPa. As a next step, average profiles corresponding, respectively, to the highest and the lowest ozone mixing ratios for the 0-1.5km layer over Cairo in summer are examined along with their corresponding composite maps of geopotential height (and anomalies), vertical velocity (and anomalies), specific humidity anomalies, precipitable water anomalies, air temperature anomalies and wind speed at 850 hPa as well as the corresponding backward trajectories. Based on the above analysis, it turns out that the lower-tropospheric ozone variability over the eastern Mediterranean area 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 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. Also, during the 7% highest ozone days at the 0-1.5km layer over Cairo, very high ozone concentrations of about 80 ppb on average are observed from the surface up to 4-5 km altitude. During the highest ozone days over both airports for the 1.5-5km layer and over Cairo over the 0-1.5km layer, there are extended regions of strong subsidence in the eastern Mediterranean but also in eastern and northern Europe and over these regions the atmosphere is dryer than average. The results of this study will be used within the framework of the MACC project. References Kalabokas, P. D., Cammas, J.-P., Thouret, V., Volz-Thomas, A., Boulanger, D. and Repapis C.C. 2013. Examination of the atmospheric conditions associated with high and low summer ozone levels in the lower troposphere over the eastern Mediterranean. Atmos. Chem. Phys. 13, 10339-10352. DOI: http://dx.doi.org/10.5194/acp-13-10339-2013 Kalabokas P. D., Thouret V., Cammas J.-P., Volz-thomas A., Boulanger D., Repapis C.C., 2015. The geographical distribution of meteorological parameters associated with high and low summer ozone levels in the lower troposphere and the boundary layer over the eastern Mediterranean (Cairo case), Tellus B, 67, 27853, http://dx.doi.org/10.3402/tellusb.v67.27853.

Reconciliation of Halogen-Induced Ozone Loss with the Total-Column Ozone Record

NASA Technical Reports Server (NTRS)

Shepherd, T. G.; Plummer, D. A.; Scinocca, J. F.; Hegglin, M. I.; Fioletov, V. E.; Reader, M. C.; Remsberg, E.; von Clarmann, T.; Wang, H. J.

2014-01-01

The observed depletion of the ozone layer from the 1980s onwards is attributed to halogen source gases emitted by human activities. However, the precision of this attribution is complicated by year-to-year variations in meteorology, that is, dynamical variability, and by changes in tropospheric ozone concentrations. As such, key aspects of the total-column ozone record, which combines changes in both tropospheric and stratospheric ozone, remain unexplained, such as the apparent absence of a decline in total-column ozone levels before 1980, and of any long-term decline in total-column ozone levels in the tropics. Here we use a chemistry-climate model to estimate changes in halogen-induced ozone loss between 1960 and 2010; the model is constrained by observed meteorology to remove the eects of dynamical variability, and driven by emissions of tropospheric ozone precursors to separate out changes in tropospheric ozone. We show that halogen-induced ozone loss closely followed stratospheric halogen loading over the studied period. Pronounced enhancements in ozone loss were apparent in both hemispheres following the volcanic eruptions of El Chichon and, in particular, Mount Pinatubo, which significantly enhanced stratospheric aerosol loads. We further show that approximately 40% of the long-term non-volcanic ozone loss occurred before 1980, and that long-term ozone loss also occurred in the tropical stratosphere. Finally, we show that halogeninduced ozone loss has declined by over 10% since stratospheric halogen loading peaked in the late 1990s, indicating that the recovery of the ozone layer is well underway.

Influence of the West Pacific subtropical high on surface ozone daily variability in summertime over eastern China

NASA Astrophysics Data System (ADS)

Zhao, Zijian; Wang, Yuxuan

2017-12-01

The West Pacific subtropical high (WPSH), as one of the most important components of the East Asian summer monsoon (EASM), is the key synoptic-scale circulation pattern influencing summertime precipitation and atmospheric conditions in China. Here we investigate the impacts of the WPSH on surface ozone daily variability over eastern China, using observations from recently established network of ozone monitors and meteorology reanalysis data during summer (June, July, August; JJA) 2014-2016 with a focus on 2014. An empirical orthogonal function (EOF) analysis of daily ozone variations reveals that the dominating eigenvector (EOF1), which contributes a quarter (25.2%) to the total variances, is a marked north-south contrast. This pattern is temporally well correlated (r = -0.66, p < 0.01) with daily anomalies of a normalized WPSH intensity index (WPSH-I). Spatially, the WPSH-I and ozone correlation is positive in North China (NC) but negative in South China (SC), which well correlates with the ozone EOF1 pattern showing the same north-south contrast (r = -0.86, p < 0.01). These associations suggest the dominant component of surface ozone daily variability in eastern China is linked with the variability of the WPSH intensity in that a stronger WPSH leads to a decrease of surface ozone over SC but an increase over NC and vice versa. This is because a stronger WPSH enhances southwesterly transport of moisture into SC, creating such conditions not conducive for ozone formation as higher RH, more cloudiness and precipitation, less UV radiation, and lower temperature. Meanwhile, as most of the rainfall due to the enhanced southwesterly transport of moisture occurs in SC, water vapor is largely depleted in the air masses transported towards NC, creating dry and sunny conditions over NC under a strong WPSH, thereby promoting ozone formation.

Analysis and interpretation of variabilities in ozone and temperature fields

NASA Technical Reports Server (NTRS)

Chandra, S.

1990-01-01

The temporal and spatial variabilities were studied of short and long term fluctuations in stratospheric ozone and temperature at various pressure levels using several years of ozone, temperature, and solar flux data from Nimbus 4, Nimbus 7, and SME satellites. Some results are as follows: (1) the solar UV flux and various indices of solar activity indicate a strong period at about 5 months; (2) satellite total ozone observations were analyzed using 17 years of data from the Nimbus 4 BUV and the Nimbus 7 SBUV experiments, which show very similar seasonal variations and quasibiennial oscillation (QBO) with some indication of a 4 year component; and (3) the zonal characteristics of both the ozone and temperature trends were derived from ten years of total ozone and 50 mb temperature based on the Nimbus 7 TOMS measurements and the NMC analyses respectively.

Tropospheric ozone long term trend observed by lidar and ECC ozonesondes at Observatoire de Haute Provence, Southern France.

NASA Astrophysics Data System (ADS)

Ancellet, G.; Gaudel, A.; Godin-Beekmann, S.

2016-12-01

Tropospheric ozone vertical profile measurements have been carried out at OHP (Observatoire de Haute Provence, 44°N, 6.7°E, 690 m) since 1991 using both UV DIAL (DIfferential Absorption Lidar) and ECC (Electrochemical Concentration Cell) ozonesondes. For the first time, ECC and lidar data measured at the same site, have been compared over a 24 year period. The comparison conducted reveals a bias between both measurement types (ECC - lidar) of the order of 0.6 ppbv. The measurements of both instruments have been however combined to decrease the impact of short-term atmospheric variability on the trend estimate. Air mass trajectories have been calculated for all the ozone observations available at OHP including ECMWF potential vorticity (PV) and humidity chnage along the trajectories. The interannual ozone variability shows a negligible trend in the mid troposphere, but a 0.36 ppbv/year significant positive ozone trend in the upper troposphere. The trends will be discussed using the variability of the meteorological parameters. Data clustering using PV and air mass trajectories is useful to identify the role of Stratosphere-Tropopshere Exchanges and long range transport of pollutants in the observed long term trends. In the lower troposphere, the interannual variability shows contrasted trends with an ozone decrease between 1998 and 2008, consistent with the NOx emission decrease, but a new period of ozone increase since 2008 which is not very well understood.

Ozone Variability and Anomalies Observed During SENEX and SEAC4RS Campaigns in 2013

NASA Astrophysics Data System (ADS)

Kuang, Shi; Newchurch, Michael J.; Thompson, Anne M.; Stauffer, Ryan M.; Johnson, Bryan J.; Wang, Lihua

2017-10-01

Tropospheric ozone variability occurs because of multiple forcing factors including surface emission of ozone precursors, stratosphere-to-troposphere transport (STT), and meteorological conditions. Analyses of ozonesonde observations made in Huntsville, AL, during the peak ozone season (May to September) in 2013 indicate that ozone in the planetary boundary layer was significantly lower than the climatological average, especially in July and August when the Southeastern United States (SEUS) experienced unusually cool and wet weather. Because of a large influence of the lower stratosphere, however, upper tropospheric ozone was mostly higher than climatology, especially from May to July. Tropospheric ozone anomalies were strongly anticorrelated (or correlated) with water vapor (or temperature) anomalies with a correlation coefficient mostly about 0.6 throughout the entire troposphere. The regression slopes between ozone and temperature anomalies for surface up to midtroposphere are within 3.0-4.1 ppbv K-1. The occurrence rates of tropospheric ozone laminae due to STT are ≥50% in May and June and about 30% in July, August, and September suggesting that the stratospheric influence on free-tropospheric ozone could be significant during early summer. These STT laminae have a mean maximum ozone enhancement over the climatology of 52 ± 33% (35 ± 24 ppbv) with a mean minimum relative humidity of 2.3 ± 1.7%.

Reducing The Station-to Station Variability of Umkehr Ozone Trends Using SAGE Measurements

NASA Technical Reports Server (NTRS)

Newchurch, Mike; Allen, Mark; Cunnold, Derek; Herman, Ben; Mateer, Carl

2000-01-01

This proposed research sought to use SAGE I and II ozone and aerosol measurements to reduce the variability in ozone trends, principally, but not exclusively, in layer 8 (40 km) derived from multiple Umkehr stations. Building on our experience with both SAGE and Umkehr data, we proposed to commence at the very beginning of the Umkehr process (measured radiance ratios) and proceed through the fitting and inversion processes in conjunction with radiative transfer calculations to establish a consistent, reliable time series of Umkehr ozone profiles at a number of stations. We expected to be able to reconcile the present discrepancies between SAGE and Umkehr trends in the upper stratosphere and, in particular, to reduce the variability in trend estimates among mid-latitude Umkehr stations.

Total ozone trends and variability during 1979-2012 from merged data sets of various satellites

NASA Astrophysics Data System (ADS)

Chehade, W.; Weber, M.; Burrows, J. P.

2014-07-01

The study presents a long-term statistical trend analysis of total ozone data sets obtained from various satellites. A multi-variate linear regression was applied to annual mean zonal mean data using various natural and anthropogenic explanatory variables that represent dynamical and chemical processes which modify global ozone distributions in a changing climate. The study investigated the magnitude and zonal distribution of the different atmospheric chemical and dynamical factors contributing to long-term total ozone changes. The regression model included the equivalent effective stratospheric chlorine (EESC), the 11-year solar cycle, the quasi-biennial oscillation (QBO), stratospheric aerosol loading describing the effects from major volcanic eruptions, the El Niño-Southern Oscillation (ENSO), the Arctic and Antarctic oscillation (AO/AAO), and accumulated eddy heat flux (EHF), the latter representing changes due to the Brewer-Dobson circulation. The total ozone column data set used here comprises the Solar Backscater Ultraviolet SBUV/SBUV-2 merged ozone data set (MOD) V8.6, the merged data set of the Solar Backscaterr Ultraviolet, the Total Ozone Mapping Spectrometer and the Ozone Monitoring Instrument SBUV/TOMS/OMI (1979-2012) MOD V8.0 and the merged data set of the Global Ozone Monitoring Experiment, the Scanning Imaging Absorption spectroMeter for Atmospheric ChartograpHY and the Global Ozone Monitoring Experiment 2 GOME/SCIAMACHY/GOME-2 (GSG) (1995-2012). The trend analysis was performed for twenty-six 5° wide latitude bands from 65° S to 65° N, and the analysis explained most of the ozone variability to within 70 to 90%. The results show that QBO dominates the ozone variability in the tropics (±7 DU) while at higher latitudes, the dynamical indices, AO/AAO and eddy heat flux, have substantial influence on total ozone variations by up to ±10 DU. The contribution from volcanic aerosols is only prominent during the major eruption periods (El Chichón and Mt. Pinatubo), and together with the ENSO signal, is more evident in the Northern Hemisphere. The signature of the solar cycle covers all latitudes and contributes about 10 DU from solar maximum to solar minimum. EESC is found to be a main contributor to the long-term ozone decline and the trend changes after the end of the 1990s. From the EESC fits, statistically significant upward trends after 1997 were found in the extratropics, which points at the slowing of ozone decline and the onset of ozone recovery. The EESC based trends are compared with the trends obtained from the statistical piecewise linear trend (PWLT) model (known as hockey stick) with a turnaround in 1997 to examine the differences between both approaches. In case of the SBUV merged V8.6 data the EESC and PWLT trends before and after 1997 are in good agreement (within 2 σ), however, the positive post-1997 linear trends from the PWLT regression are not significant within 2 σ. A sensitivity study is carried out by comparing the regression results, using SBUV/SBUV-2 MOD V8.6 merged time series (1979-2012) and a merged data set combining SBUV/SBUV-2 (1979-June 1995) and GOME/SCIAMACHY/GOME-2 ("GSG") WFDOAS (Weighting Function DOAS) (July 1995-2012) as well as SBUV/TOMS/OMI MOD V8.0 (1979-2012) in the regression analysis in order to investigate the uncertainty in the long-term trends due to different ozone data sets and data versions. Replacing the late SBUV/SBUV-2 merged data record with GSG data (unscaled and adjusted) leads to very similar results demonstrating the high consistency between satellite data sets. However, the comparison of the new SBUV/SBUV-2 MOD V8.6 with the MOD V8.0 and MOD8.6/GSG data showed somewhat smaller sensitivities with regard to several proxies as well as the linear EESC trends. On the other hand, the PWLT trends after 1997 show some differences, however, within the 2 σ error bars the PWLT trends agree with each other for all three data sets.

Tropical Tropospheric Ozone Climatology: Approaches Based on SHADOZ Observations

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacquelyn C.; Chatfield, Robert B.; Hudson, Robert D.; Andrade, Marcos; Coetzee, Geert J. R.; Posny, Francoise

2004-01-01

The SHADOZ (Southern Hemisphere Additional Ozonesondes) ozone sounding network was initiated in 1998 to improve the coverage of tropical in-situ ozone measurements for satellite validation, algorithm development and related process studies. Over 2000 soundings have been archived at the central website, , for 12 stations that span the entire equatorial zone [Thompson et al., JGR, 108,8238, 2003]. The most striking features of tropospheric ozone profiles in SHADOZ are: (1) persistent longitudinal variability in tropospheric ozone profiles, with a 10-15 DU column-integrated difference between Atlantic and Pacific sites; (2) intense short-term variability triggered by changing meteorological conditions and advection of pollution. The implications of these results for profile climatologies and trends are described along with several approaches to classifying ozone profiles: 1) Seasonal means during MAM (March-April-May) and SON (September-October-November); 2) Maxima and minima, identified through correlation of TOMS-derived TTO (tropical tropospheric ozone) column depth with the sonde integrated tropospheric ozone column; and 3) Meteorological regimes, a technique that is effective in the subtropics where tropical and mid-latitude conditions alternate.

The 1998-2000 SHADOZ (Southern Hemisphere ADditional OZonesondes) Tropical Ozone Climatology. 2; Stratospheric and Tropospheric Ozone Variability and the Zonal Wave-One

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Schmidlin, Francis J.; Logan, Jennifer A.; Fujiwara, Masatomo; Kirchhoff, Volker W. J. H.; Posny, Francoise; Coetzee, Gert J. R.; Hoegger, Bruno;

On the interannual oscillations in the northern temperate total ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krzyscin, J.W.

1994-07-01

The interannual variations in total ozone are studied using revised Dobson total ozone records (1961-1990) from 17 stations located within the latitude band 30 deg N - 60 deg N. To obtain the quasi-biennial oscillation (QBO), El Nino-Southern Oscillation (ENSO), and 11-year solar cycle manifestation in the `northern temperate` total ozone data, various multiple regression models are constructed by the least squares fitting to the observed ozone. The statistical relationships between the selected indices of the atmospheric variabilities and total ozone are described in the linear and nonlinear regression models. Nonlinear relationships to the predictor variables are found. That is,more » the total ozone variations are statistically modeled by nonlinear terms accounting for the coupling between QBO and ENSO, QBO and solar activity, and ENSO and solar activity. It is suggested that large reduction of total ozone values over the `northern temperate` region occurs in cold season when a strong ENSO warm event meets the west phase of the QBO during the period of high solar activity.« less

On the Identification of Ozone Recovery

NASA Astrophysics Data System (ADS)

Stone, Kane A.; Solomon, Susan; Kinnison, Douglas E.

2018-05-01

As ozone depleting substances decline, stratospheric ozone is displaying signs of healing in the Antarctic lower stratosphere. Here we focus on higher altitudes and the global stratosphere. Two key processes that can influence ozone recovery are evaluated: dynamical variability and solar proton events (SPEs). A nine-member ensemble of free-running simulations indicates that dynamical variability dominates the relatively small ozone recovery signal over 1998-2016 in the subpolar lower stratosphere, particularly near the tropical tropopause. The absence of observed recovery there to date is therefore not unexpected. For the upper stratosphere, high latitudes (50-80°N/S) during autumn and winter show the largest recovery. Large halogen-induced odd oxygen loss there provides a fingerprint of seasonal sensitivity to chlorine trends. However, we show that SPEs also have a profound effect on ozone trends within this region since 2000. Thus, accounting for SPEs is important for detection of recovery in the upper stratosphere.

Discoveries about Tropospheric Ozone Pollution from Satellite and Soundings

NASA Technical Reports Server (NTRS)

Thompson, Anne M.

2004-01-01

We have been producing near-red time tropospheric ozone satellite maps from the TOMS (Total Ozone Mapping Spectrometer) sensor since 1997. Maps for 1996-2000 for the operational Earth-Probe instrument are at:. Pollution in the tropics is influenced by biomass burning and by transport patterns that favor recirculation and in other cases reflect climate variability like the El-Nino-Southern Oscillation [Thompson et al., 2001]. The satellite view of chemical-dynamical interactions in tropospheric ozone is not adequate to capture vertical gradients in pollution. Thus, in 1998, NASA's Goddard Space Flight Center and a team of international sponsors established the SHADOZ (Southern Hemisphere ADditional OZonesondes) project to address the gap in tropical ozone soundings. SHADOZ augments launches and provides a public archive of ozonesonde data from twelve tropical stations at http://croc.gsfc.nasa.gov/shadoz. Further insights into the role of chemical and dynamical influences have emerged from the first 4-5 years of SHADOZ data (more than 2000 ozone profiles). Highly variable tropospheric ozone and a zonal wave-one pattern in tropospheric ozone suggest that dynamics is as important as pollution in determining tropical ozone distributions.

Variability and trend in ozone over the southern tropics and subtropics

NASA Astrophysics Data System (ADS)

Toihir, Abdoulwahab Mohamed; Portafaix, Thierry; Sivakumar, Venkataraman; Bencherif, Hassan; Pazmiño, Andréa; Bègue, Nelson

2018-03-01

Long-term variability in ozone trends was assessed over eight Southern Hemisphere tropical and subtropical sites (Natal, Nairobi, Ascension Island, Java, Samoa, Fiji, Reunion and Irene), using total column ozone data (TCO) and vertical ozone profiles (altitude range 15-30 km) recorded during the period January 1998-December 2012. The TCO datasets were constructed by combination of satellite data (OMI and TOMS) and ground-based observations recorded using Dobson and SAOZ spectrometers. Vertical ozone profiles were obtained from balloon-sonde experiments which were operated within the framework of the SHADOZ network. The analysis in this study was performed using the Trend-Run model. This is a multivariate regression model based on the principle of separating the variations of ozone time series into a sum of several forcings (annual and semi-annual oscillations, QBO (Quasi-Biennial Oscillation), ENSO, 11-year solar cycle) that account for most of its variability. The trend value is calculated based on the slope of a normalized linear function which is one of the forcing parameters included in the model. Three regions were defined as follows: equatorial (0-10° S), tropical (10-20° S) and subtropical (20-30° S). Results obtained indicate that ozone variability is dominated by seasonal and quasi-biennial oscillations. The ENSO contribution is observed to be significant in the tropical lower stratosphere and especially over the Pacific sites (Samoa and Java). The annual cycle of ozone is observed to be the most dominant mode of variability for all the sites and presents a meridional signature with a maximum over the subtropics, while semi-annual and quasi-biannual ozone modes are more apparent over the equatorial region, and their magnitude decreases southward. The ozone variation mode linked to the QBO signal is observed between altitudes of 20 and 28 km. Over the equatorial zone there is a strong signal at ˜ 26 km, where 58 % ±2 % of total ozone variability is explained by the effect of QBO. Annual ozone oscillations are more apparent at two different altitude ranges (below 24 km and in the 27-30 km altitude band) over the tropical and subtropical regions, while the semi-annual oscillations are more significant over the 27-30 km altitude range in the tropical and equatorial regions. The estimated trend in TCO is positive and not significant and corresponds to a variation of ˜ 1.34±0.50 % decade-1 (averaged over the three regions). The trend estimated within the equatorial region (0-15° S) is less than 1 % per decade, while it is assessed at more than 1.5 % decade-1 for all the sites located southward of 17° S. With regard to the vertical distribution of trend estimates, a positive trend in ozone concentration is obtained in the 22-30 km altitude range, while a delay in ozone improvement is apparent in the UT-LS (upper troposphere-lower stratosphere) below 22 km. This is especially noticeable at approximately 19 km, where a negative value is observed in the tropical regions.

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 measured daily ozone concentrations exceeding 65(75) ppbv, indicating their significant influence on ozone exceptional events. We further compare the wildfire ozone enhancements estimated by the statistical and Lagrangian approach with those estimated from a Eulerian model (GEOS-Chem). Despite highly-correlated results, GEOS-Chem largely overestimates wildfire ozone influences near the source regions and fails to capture ozone production from wildfires at long distance, reflecting deficiencies in current Eulerian models to capture small-scale emissions.

Upper Tropospheric Ozone Between Latitudes 60S and 60N Derived from Nimbus 7 TOMS/THIR Cloud Slicing

NASA Technical Reports Server (NTRS)

Ziemke, Jerald R.; Chandra, Sushil; Bhartia, P. K.

2002-01-01

This study evaluates the spatial distributions and seasonal cycles in upper tropospheric ozone (pressure range 200-500 hPa) from low to high latitudes (60S to 60N) derived from the satellite retrieval method called "Cloud Slicing." Cloud Slicing is a unique technique for determining ozone profile information in the troposphere by combining co-located measurements of cloud-top, pressure and above-cloud column ozone. For upper tropospheric ozone, co-located measurements of Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) above-cloud column ozone, and Nimbus 7 Temperature Humidity Infrared Radiometer (THIR) cloud-top pressure during 1979-1984 were incorporated. In the tropics, upper tropospheric ozone shows year-round enhancement in the Atlantic region and evidence of a possible semiannual variability. Upper tropospheric ozone outside the tropics shows greatest abundance in winter and spring seasons in both hemispheres with largest seasonal and largest amounts in the NH. These characteristics are similar to lower stratospheric ozone. Comparisons of upper tropospheric column ozone with both stratospheric ozone and a proxy of lower stratospheric air mass (i.e., tropopause pressure) from National Centers for Environmental Prediction (NCEP) suggest that stratosphere-troposphere exchange (STE) may be a significant source for the seasonal variability of upper tropospheric ozone almost everywhere between 60S and 60N except in low latitudes around 10S to 25N where other sources (e.g., tropospheric transport, biomass burning, aerosol effects, lightning, etc.) may have a greater role.

Seasonal prediction of US summertime ozone using statistical analysis of large scale climate patterns.

PubMed

Shen, Lu; Mickley, Loretta J

2017-03-07

We develop a statistical model to predict June-July-August (JJA) daily maximum 8-h average (MDA8) ozone concentrations in the eastern United States based on large-scale climate patterns during the previous spring. We find that anomalously high JJA ozone in the East is correlated with these springtime patterns: warm tropical Atlantic and cold northeast Pacific sea surface temperatures (SSTs), as well as positive sea level pressure (SLP) anomalies over Hawaii and negative SLP anomalies over the Atlantic and North America. We then develop a linear regression model to predict JJA MDA8 ozone from 1980 to 2013, using the identified SST and SLP patterns from the previous spring. The model explains ∼45% of the variability in JJA MDA8 ozone concentrations and ∼30% variability in the number of JJA ozone episodes (>70 ppbv) when averaged over the eastern United States. This seasonal predictability results from large-scale ocean-atmosphere interactions. Warm tropical Atlantic SSTs can trigger diabatic heating in the atmosphere and influence the extratropical climate through stationary wave propagation, leading to greater subsidence, less precipitation, and higher temperatures in the East, which increases surface ozone concentrations there. Cooler SSTs in the northeast Pacific are also associated with more summertime heatwaves and high ozone in the East. On average, models participating in the Atmospheric Model Intercomparison Project fail to capture the influence of this ocean-atmosphere interaction on temperatures in the eastern United States, implying that such models would have difficulty simulating the interannual variability of surface ozone in this region.

Stratospheric Ozone Climatology from Lidar Measurements at Table Mountain (34.0 deg N, 117.7 deg W) and Mauna Loa (19.5 deg N, 155.6 deg W)

NASA Technical Reports Server (NTRS)

Leblanc, T.; McDermid, I. S.

2000-01-01

Using more than 1600 nighttime profiles obtained by the JPL differential absorption lidars (DIAL) located at Table Mountain Facility (TMF, 34.4 N) and Mauna Loa Observatory (MLO, 19.5 N) is presented in this paper. These two systems have been providing high-resolution vertical profiles of ozone number density between 15-50 km, several nights a week since 1989 (TMF) and 1993 (MLO). The climatology presented here is typical of early night ozone values with only a small influence of the Pinatubo aerosols and the 11-year solar cycle. The observed seasonal and vertical structure of the ozone concentration at TMF is consistent with that typical of mid- to subtropical latitudes. A clear annual cycle in opposite phase below and above the ozone concentration peak is observed. The observed winter maximum below the ozone peak is associated with a maximum day-to-day variability, typical of a dynamically driven lower stratosphere. The maximum concentration observed in summer above the ozone peak emphasizes the more dominant role of photochemistry. Unlike TMF, the ozone concentration observed at MLO tends to be higher during the summer months and lower during the winter months throughout the entire stratospheric ozone layer. Only a weak signature of the extra-tropical latitudes is observed near 19-20 km, with a secondary maximum in late winter. The only large variability observed at MLO is associated with the natural variability of the tropical tropopause.

Seasonal prediction of US summertime ozone using statistical analysis of large scale climate patterns

PubMed Central

Mickley, Loretta J.

2017-01-01

We develop a statistical model to predict June–July–August (JJA) daily maximum 8-h average (MDA8) ozone concentrations in the eastern United States based on large-scale climate patterns during the previous spring. We find that anomalously high JJA ozone in the East is correlated with these springtime patterns: warm tropical Atlantic and cold northeast Pacific sea surface temperatures (SSTs), as well as positive sea level pressure (SLP) anomalies over Hawaii and negative SLP anomalies over the Atlantic and North America. We then develop a linear regression model to predict JJA MDA8 ozone from 1980 to 2013, using the identified SST and SLP patterns from the previous spring. The model explains ∼45% of the variability in JJA MDA8 ozone concentrations and ∼30% variability in the number of JJA ozone episodes (>70 ppbv) when averaged over the eastern United States. This seasonal predictability results from large-scale ocean–atmosphere interactions. Warm tropical Atlantic SSTs can trigger diabatic heating in the atmosphere and influence the extratropical climate through stationary wave propagation, leading to greater subsidence, less precipitation, and higher temperatures in the East, which increases surface ozone concentrations there. Cooler SSTs in the northeast Pacific are also associated with more summertime heatwaves and high ozone in the East. On average, models participating in the Atmospheric Model Intercomparison Project fail to capture the influence of this ocean–atmosphere interaction on temperatures in the eastern United States, implying that such models would have difficulty simulating the interannual variability of surface ozone in this region. PMID:28223483

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.

Extraction of wind and temperature information from hybrid 4D-Var assimilation of stratospheric ozone using NAVGEM

NASA Astrophysics Data System (ADS)

Allen, Douglas R.; Hoppel, Karl W.; Kuhl, David D.

2018-03-01

Extraction of wind and temperature information from stratospheric ozone assimilation is examined within the context of the Navy Global Environmental Model (NAVGEM) hybrid 4-D variational assimilation (4D-Var) data assimilation (DA) system. Ozone can improve the wind and temperature through two different DA mechanisms: (1) through the flow-of-the-day ensemble background error covariance that is blended together with the static background error covariance and (2) via the ozone continuity equation in the tangent linear model and adjoint used for minimizing the cost function. All experiments assimilate actual conventional data in order to maintain a similar realistic troposphere. In the stratosphere, the experiments assimilate simulated ozone and/or radiance observations in various combinations. The simulated observations are constructed for a case study based on a 16-day cycling truth experiment (TE), which is an analysis with no stratospheric observations. The impact of ozone on the analysis is evaluated by comparing the experiments to the TE for the last 6 days, allowing for a 10-day spin-up. Ozone assimilation benefits the wind and temperature when data are of sufficient quality and frequency. For example, assimilation of perfect (no applied error) global hourly ozone data constrains the stratospheric wind and temperature to within ˜ 2 m s-1 and ˜ 1 K. This demonstrates that there is dynamical information in the ozone distribution that can potentially be used to improve the stratosphere. This is particularly important for the tropics, where radiance observations have difficulty constraining wind due to breakdown of geostrophic balance. Global ozone assimilation provides the largest benefit when the hybrid blending coefficient is an intermediate value (0.5 was used in this study), rather than 0.0 (no ensemble background error covariance) or 1.0 (no static background error covariance), which is consistent with other hybrid DA studies. When perfect global ozone is assimilated in addition to radiance observations, wind and temperature error decreases of up to ˜ 3 m s-1 and ˜ 1 K occur in the tropical upper stratosphere. Assimilation of noisy global ozone (2 % errors applied) results in error reductions of ˜ 1 m s-1 and ˜ 0.5 K in the tropics and slightly increased temperature errors in the Northern Hemisphere polar region. Reduction of the ozone sampling frequency also reduces the benefit of ozone throughout the stratosphere, with noisy polar-orbiting data having only minor impacts on wind and temperature when assimilated with radiances. An examination of ensemble cross-correlations between ozone and other variables shows that a single ozone observation behaves like a potential vorticity (PV) charge, or a monopole of PV, with rotation about a vertical axis and vertically oriented temperature dipole. Further understanding of this relationship may help in designing observation systems that would optimize the impact of ozone on the dynamics.

Evaluating the effects of climate change on summertime ozone using a relative response factor approach for policymakers.

PubMed

Avise, Jeremy; Abraham, Rodrigo Gonzalez; Chung, Serena H; Chen, Jack; Lamb, Brian; Salathé, Eric P; Zhang, Yongxin; Nolte, Christopher G; Loughlin, Daniel H; Guenther, Alex; Wiedinmyer, Christine; Duhl, Tiffany

2012-09-01

The impact of climate change on surface-level ozone is examined through a multiscale modeling effort that linked global and regional climate models to drive air quality model simulations. Results are quantified in terms of the relative response factor (RRF(E)), which estimates the relative change in peak ozone concentration for a given change in pollutant emissions (the subscript E is added to RRF to remind the reader that the RRF is due to emission changes only). A matrix of model simulations was conducted to examine the individual and combined effects offuture anthropogenic emissions, biogenic emissions, and climate on the RRF(E). For each member in the matrix of simulations the warmest and coolest summers were modeled for the present-day (1995-2004) and future (2045-2054) decades. A climate adjustment factor (CAF(C) or CAF(CB) when biogenic emissions are allowed to change with the future climate) was defined as the ratio of the average daily maximum 8-hr ozone simulated under a future climate to that simulated under the present-day climate, and a climate-adjusted RRF(EC) was calculated (RRF(EC) = RRF(E) x CAF(C)). In general, RRF(EC) > RRF(E), which suggests additional emission controls will be required to achieve the same reduction in ozone that would have been achieved in the absence of climate change. Changes in biogenic emissions generally have a smaller impact on the RRF(E) than does future climate change itself The direction of the biogenic effect appears closely linked to organic-nitrate chemistry and whether ozone formation is limited by volatile organic compounds (VOC) or oxides of nitrogen (NO(x) = NO + NO2). Regions that are generally NO(x) limited show a decrease in ozone and RRF(EC), while VOC-limited regions show an increase in ozone and RRF(EC). Comparing results to a previous study using different climate assumptions and models showed large variability in the CAF(CB). We present a methodology for adjusting the RRF to account for the influence of climate change on ozone. The findings of this work suggest that in some geographic regions, climate change has the potential to negate decreases in surface ozone concentrations that would otherwise be achieved through ozone mitigation strategies. In regions of high biogenic VOC emissions relative to anthropogenic NO(x) emissions, the impact of climate change is somewhat reduced, while the opposite is true in regions of high anthropogenic NO(x) emissions relative to biogenic VOC emissions. Further, different future climate realizations are shown to impact ozone in different ways.

Modeling ozone bioindicator injury with microscale and landscape-scale explanatory variables: A logistic regression approach

Treesearch

John W. Coulston

2011-01-01

Tropospheric ozone occurs at phytotoxic levels in the United States (Lefohn and Pinkerton 1988). Several plant species, including commercially important timber species, are sensitive to elevated ozone levels. Exposure to elevated ozone can cause growth reduction and foliar injury and make trees more susceptible to secondary stressors such as insects and pathogens (...

NOx Emissions from Large Point Sources: Variability in Ozone Production, Resulting Health Damages and Economic Costs

NASA Astrophysics Data System (ADS)

Mauzerall, D. L.; Sultan, B.; Kim, N.; Bradford, D.

2004-12-01

We present a proof-of-concept analysis of the measurement of the health damage of ozone (O3) produced from nitrogen oxides (NOx = NO + NO2) emitted by individual large point sources in the eastern United States. We use a regional atmospheric model of the eastern United States, the Comprehensive Air Quality Model with Extensions (CAMx), to quantify the variable impact that a fixed quantity of NOx emitted from individual sources can have on the downwind concentration of surface O3, depending on temperature and local biogenic hydrocarbon emissions. We also examine the dependence of resulting ozone-related health damages on the size of the exposed population. The investigation is relevant to the increasingly widely used "cap and trade" approach to NOx regulation, which presumes that shifts of emissions over time and space, holding the total fixed over the course of the summer O3 season, will have minimal effect on the environmental outcome. By contrast, we show that a shift of a unit of NOx emissions from one place or time to another could result in large changes in the health effects due to ozone formation and exposure. We indicate how the type of modeling carried out here might be used to attach externality-correcting prices to emissions. Charging emitters fees that are commensurate with the damage caused by their NOx emissions would create an incentive for emitters to reduce emissions at times and in locations where they cause the largest damage.

Interannual variability of the Antarctic ozone hole in a GCM. Part 2: A comparison of unforced and QBO-induced variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shindell, D.T.; Rind, D.; Balachandran, N.

1999-06-15

Simulations were performed with the Goddard Institute for Space Studies GCM including a prescribed quasi-biennial oscillation (QBO), applied at a constant maximum value, and a physically realistic parameterization of the heterogeneous chemistry responsible for severe polar ozone loss. While the QBO is primarily a stratospheric phenomenon, in this model the QBO modulates the amount and propagation of planetary wave energy in the troposphere as well as in the stratosphere. Dynamical activity is greater in the easterly than in the unforced case, while westerly years are dynamically more quiescent. By altering zonal winds and potential vorticity, the QBO forcing changes themore » refraction of planetary waves beginning in midwinter, causing the lower-stratospheric zonal average temperatures at Southern Hemisphere high latitudes to be [approximately]3--5 K warmer in the easterly phase than in the westerly during the late winter and early spring. Ozone loss varies nonlinearly with temperature, due to the sharp threshold for formation of heterogeneous chemistry surfaces, so that the mean daily total mass of ozone depleted in this region during September was 8.7 [times] 10[sup 10] kg in the QBO easterly maximum, as compared with 12.0 [times] 10[sup 10] kg in the westerly maximum and 10.3 [times] 10[sup 10] kg in the unforced case. Through this mechanism, the midwinter divergence of the Eliassen-Palm flux is well correlated with the subsequent springtime total ozone loss (R[sup 2] = 0.6). The chemical ozone loss differences are much larger than QBO-induced transport differences in the authors' model. Inclusion of the QBO forcing also increased the maximum variability in total ozone loss from the [approximately]20% value found in the unforced runs to [approximately]50%. These large variations in ozone depletion are very similar in size to the largest observed variations in the severity of the ozone hole. The results suggest that both random variability and periodic QBO forcing are important components, perhaps explaining some of the difficulties encountered in previous attempts to correlate the severity of the ozone hole with the QBO phase.« less

Attribution of Trends and Variability in Surface Ozone over the United States

NASA Technical Reports Server (NTRS)

Strode, Sarah; Cooper, Owen; Damo, Megan; Logan, Jennifer; Rodriquez, Jose; Strahan, Susan; Witte, Jacquie

2013-01-01

Concentrations of tropospheric ozone, a greenhouse gas and air pollutant, are impacted by changes in precursor emissions as well meteorology and influx from the stratosphere. Observations show a decreasing trend in summertime surface ozone at rural stations in the eastern United States, while some western stations show increasing trends, particularly in springtime. We use the Global Modeling Initiative (GMI) global chemical transport model to investigate the roles of precursor emission changes, meteorological variability, and stratosphere-troposphere exchange (STE) in explaining observed trends in surface ozone from rural sites in the United States from 1991-2010. The model's interannual variability shows significant correlations with observations from many of the surface sites. We also compare the simulated ozone to ozonesonde data for several locations with sufficiently long records. We compare a simulation with time-dependent precursor emissions, including emission reductions over the United States and Europe and increases over Asia, to a simulation with fixed emissions to quantify the impact of changing emissions on the surface trends. The simulation with varying emissions reproduces much of the east-west difference in summertime ozone over the U.S., although it generally underestimates the negative trend in the East. In contrast, the fixed-emission simulation shows increasing ozone at both eastern and western sites. We will discuss possible causes of this behavior, including long-range transport and STE.

Changing Conditions in the Arctic: An Analysis of 45 years of Tropospheric Ozone Measurements at Barrow Observatory

NASA Astrophysics Data System (ADS)

McClure-Begley, A.; Petropavlovskikh, I. V.; Crepinsek, S.; Jefferson, A.; Emmons, L. K.; Oltmans, S. J.

2017-12-01

In order to understand the impact of climate on local bio-systems, understanding the changes to the atmospheric composition and processes in the Arctic boundary layer and free troposphere is imperative. In the Arctic, many conditions influence tropospheric ozone variability such as: seasonal halogen caused depletion events, long range transport of pollutants from mid-northern latitudes, compounds released from wildfires, and different meteorological conditions. The Barrow station in Utqiagvik, Alaska has collected continuous measurements of ground-level ozone since 1973. This unique long-term time series allows for analysis of the influence of a rapidly changing climate on ozone conditions in this region. Specifically, this study analyzes the frequency of enhanced ozone episodes over time and provides in depth analysis of periods of positive deviations from the expected conditions. To discern the contribution of different pollutant sources to observed ozone variability, co-located measurements of aerosols, carbon monoxide, and meteorological conditions are used. In addition, the NCAR Mozart-4/MOPITT Chemical Forecast model and NOAA Hysplit back-trajectory analysis provide information on transport patterns to the Arctic and confirmation of the emission sources that influenced the observed conditions. These anthropogenic influences on ozone variability in and below the boundary layer are essential for developing an understanding of the interaction of climate change and the bio-systems in the Arctic.

VOC Reactivity and the Ozone Climate Penalty: Modeled Impacts of Updated Aromatic and Monoterpene Chemistry on the Ozone-temperature Connection

NASA Astrophysics Data System (ADS)

Porter, W. C.; Heald, C. L.; Safieddine, S.

2016-12-01

Rising temperatures associated with global warming can increase concentrations of tropospheric ozone (O3) in many regions worldwide, a correlation often described as the "ozone climate penalty". This effect is driven by a variety of underlying chemical, physical, and biological mechanisms, including temperature-dependent reaction rates, emissions of volatile organic compounds (VOCs) from trees and other plant life, and correlations with other meteorological variables. While many of the most important O3-producing VOCs, such as isoprene, are represented in typical chemical transport models such as GEOS-Chem, others - including aromatics from fires and human activity and monoterpenes from natural sources - are not always included in gas-phase chemistry. Here we examine the impact of increased VOC reactivity on the ozone climate penalty due to a more comprehensive treatment of aromatics and monoterpenes in the chemical transport model GEOS-Chem, finding regional impacts not only on daily O3 levels themselves, but also on the O3/temperature relationship. While many uncertainties related to the emissions and chemistry of these species remain, the impact of their inclusion on both current simulations and future projections indicates their importance towards the overall goal of more accurately modeled surface O3.

BROMIDE'S EFFECT ON DBP FORMATION, SPECIATION, AND CONTROL: PART 1, OZONATION

EPA Science Inventory

The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection byproducts (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalometha...

Ozone Exposure-Response in Field Grown Soybean: Characterizing Intraspecific Variability of Physiology and Biochemistry

USDA-ARS?s Scientific Manuscript database

Crop losses due to rising tropospheric ozone concentrations ([ozone]) in 2000 were estimated to cost $1.8 to $3.9 billion in the U.S. and $3.0 to $5.5 billion in China, and are expected to grow with the predicted 25% increase in background [ozone] over the next 30 to 50 years. This challenge provide...

SHADOZ (Southern Hemisphere Additional Ozonesondes): A Project Overview and New Insights on Tropical Tropospheric Ozone

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacquelyn C.; Oltmans, S. J.; Schmidlin, F. J.

2004-01-01

The SHADOZ (Southern Hemisphere Additional Ozonesondes) ozone sounding network was initiated in 1998 to improve the coverage of tropical in-situ ozone measurements for satellite validation, algorithm development and related process studies. Over 2000 soundings have been archived at the website, http://croc.gsfc.nasa.gov/shadoz, for 12 stations: Ascension Island; Nairobi and Malindi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil; Paramaribo, Surinam. Key results from SHADOZ will be described from among the following: 1) By using ECC sondes with similar procedures, 5-10% accuracy and precision (1-sigma) of the sonde total ozone measurement is achieved; 2) Week-to-week variability in tropospheric ozone is so great that statistics are frequently not Gaussian; most stations vary up to a factor of 3 in tropospheric column over the course of a year; 3) Longitudinal variability in tropospheric ozone profiles is a consistent feature, with a 10-15 DU column-integrated difference between Atlantic and Pacific sites; this causes a "zonal wave-one" feature in total ozone; 4) The ozone record from Paramaribo, Surinam (6N, 55W) is a marked contrast to southern tropical ozone because Surinam is often north of the Intertropical Convergence Zone.

Mirrored changes in Antarctic ozone and stratospheric temperature in the late 20th versus early 21st centuries

NASA Astrophysics Data System (ADS)

Solomon, Susan; Ivy, Diane; Gupta, Mukund; Bandoro, Justin; Santer, Benjamin; Fu, Qiang; Lin, Pu; Garcia, Rolando R.; Kinnison, Doug; Mills, Michael

2017-08-01

Observed and modeled patterns of lower stratospheric seasonal trends in Antarctic ozone and temperature in the late 20th (1979-2000) and the early 21st (2000-2014) centuries are compared. Patterns of pre-2000 observed Antarctic ozone decreases and stratospheric cooling as a function of month and pressure are followed by opposite-signed (i.e., "mirrored") patterns of ozone increases and warming post-2000. An interactive chemistry-climate model forced by changes in anthropogenic ozone depleting substances produces broadly similar mirrored features. Statistical analysis of unforced model simulations (from long-term model control simulations of a few centuries up to 1000 years) suggests that internal and solar natural variability alone is unable to account for the pattern of observed ozone trend mirroring, implying that forcing is the dominant driver of this behavior. Radiative calculations indicate that ozone increases have contributed to Antarctic warming of the lower stratosphere over 2000-2014, but dynamical changes that are likely due to internal variability over this relatively short period also appear to be important. Overall, the results support the recent finding that the healing of the Antarctic ozone hole is underway and that coupling between dynamics, chemistry, and radiation is important for a full understanding of the causes of observed stratospheric temperature and ozone changes.

Screening agrochemicals as potential protectants of plants against ozone phytotoxicity.

PubMed

Saitanis, Costas J; Lekkas, Dimitrios V; Agathokleous, Evgenios; Flouri, Fotini

2015-02-01

We tested seven contemporary agrochemicals as potential plant protectants against ozone phytotoxicity. In nine experiments, Bel-W3 tobacco plants were experienced weekly exposures to a) 80 nmol mol(-1) of ozone-enriched or ozone-free air in controlled environment chambers, b) an urban air polluted area, and c) an agricultural-remote area. Ozone caused severe leaf injury, reduced chlorophylls' and total carotenoids' content, and negatively affected photosynthesis and stomatal conductance. Penconazole, (35% ± 8) hexaconazole (28% ± 5) and kresoxim-methyl (28% ± 15) showed higher plants' protection (expressed as percentage; mean ± s.e.) against ozone, although the latter exhibited a high variability. Azoxystrobin (21% ± 15) showed lower protection efficacy and Benomyl (15% ± 9) even lower. Trifloxystrobin (7% ± 11) did not protect the plants at all. Acibenzolar-S-methyl + metalaxyl-M (Bion MX) (-6% ± 17) exhibited the higher variability and contrasting results: in some experiments it showed some protection while in others it intensified the ozone injury by causing phytotoxic symptoms on leaves, even in control plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Detecting recovery of the stratospheric ozone layer.

PubMed

Chipperfield, Martyn P; Bekki, Slimane; Dhomse, Sandip; Harris, Neil R P; Hassler, Birgit; Hossaini, Ryan; Steinbrecht, Wolfgang; Thiéblemont, Rémi; Weber, Mark

2017-09-13

As a result of the 1987 Montreal Protocol and its amendments, the atmospheric loading of anthropogenic ozone-depleting substances is decreasing. Accordingly, the stratospheric ozone layer is expected to recover. However, short data records and atmospheric variability confound the search for early signs of recovery, and climate change is masking ozone recovery from ozone-depleting substances in some regions and will increasingly affect the extent of recovery. Here we discuss the nature and timescales of ozone recovery, and explore the extent to which it can be currently detected in different atmospheric regions.

Detecting recovery of the stratospheric ozone layer

NASA Astrophysics Data System (ADS)

Chipperfield, Martyn P.; Bekki, Slimane; Dhomse, Sandip; Harris, Neil R. P.; Hassler, Birgit; Hossaini, Ryan; Steinbrecht, Wolfgang; Thiéblemont, Rémi; Weber, Mark

2017-09-01

As a result of the 1987 Montreal Protocol and its amendments, the atmospheric loading of anthropogenic ozone-depleting substances is decreasing. Accordingly, the stratospheric ozone layer is expected to recover. However, short data records and atmospheric variability confound the search for early signs of recovery, and climate change is masking ozone recovery from ozone-depleting substances in some regions and will increasingly affect the extent of recovery. Here we discuss the nature and timescales of ozone recovery, and explore the extent to which it can be currently detected in different atmospheric regions.

Trends in total column ozone measurements

NASA Technical Reports Server (NTRS)

Rowland, F. S.; Angell, J.; Attmannspacher, W.; Bloomfield, P.; Bojkov, R. D.; Harris, N.; Komhyr, W.; Mcfarland, M.; Mcpeters, R.; Stolarski, R. S.

1989-01-01

It is important to ensure the best available data are used in any determination of possible trends in total ozone in order to have the most accurate estimates of any trends and the associated uncertainties. Accordingly, the existing total ozone records were examined in considerable detail. Once the best data set has been produced, the statistical analysis must examine the data for any effects that might indicate changes in the behavior of global total ozone. The changes at any individual measuring station could be local in nature, and herein, particular attention was paid to the seasonal and latitudinal variations of total ozone, because two dimensional photochemical models indicate that any changes in total ozone would be most pronounced at high latitudes during the winter months. The conclusions derived from this detailed examination of available total ozone can be split into two categories, one concerning the quality and the other the statistical analysis of the total ozone record.

Variability in Ozone-Induced Pulmonary Injury and Inflammation in Healthy and Cardiovascular Compromised Rat Models

EPA Science Inventory

The molecular bases for variability in air pollutant-induced pulmonary injury due to underlying cardiovascular (CVD) and/or metabolic diseases are unknown. We hypothesized that healthy and genetic CVD-prone rat models will exhibit exacerbated response to acute ozone exposure depe...

Influence of ozone and meteorological parameters on levels of polycyclic aromatic hydrocarbons in the air

NASA Astrophysics Data System (ADS)

Pehnec, Gordana; Jakovljević, Ivana; Šišović, Anica; Bešlić, Ivan; Vađić, Vladimira

2016-04-01

Concentrations of ten polycyclic aromatic hydrocarbons (PAHs) in the PM10 particle fraction were measured together with ozone and meteorological parameters at an urban site (Zagreb, Croatia) over a one-year period. Data were subjected to regression analysis in order to determine the relationship between the measured pollutants and selected meteorological variables. All of the PAHs showed seasonal variations with high concentrations in winter and autumn and very low concentrations during summer and spring. All of the ten PAHs concentrations also correlated well with each other. A statistically significant negative correlation was found between the concentrations of PAHs and ozone concentrations and concentrations of PAHs and temperature, as well as a positive correlation between concentrations of PAHs and PM10 mass concentration and relative humidity. Multiple regression analysis showed that concentrations of PM10 and ozone, temperature, relative humidity and pressure accounted for 43-70% of PAHs variability. Concentrations of PM10 and temperature were significant variables for all of the measured PAH's concentrations in all seasons. Ozone concentrations were significant for only some of the PAHs, particularly 6-ring PAHs.

UARS Microwave Limb Sounder Observations of Upper Atmosphere Ozone and Chlorine Monoxide

NASA Technical Reports Server (NTRS)

Flower, D.; Froidevaux, L.; Jarnot, R.; Read, W.; Waters, J.

1994-01-01

UARS MLS observations of stratospheric ozone and chlorine monoxide are described. Enhanced concentrations of ClO, the predominant form of reactive chlorine responsible for ozone depletion, are seen within both the northern and southern winter polar vortices. In the southern hemisphere, this leads directly to the development of the annual Antarctic ozone hole. While ozone depletion is also observed in the north, it is less severe and there is considerable interannual variability.

Atmospheric Chemistry Insights from the SHADOZ Data: An IGAC Paradigm

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Bhartia, P. K. (Technical Monitor)

2002-01-01

The first climatological overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropical and subtropics is based on ozone sounding data from ten sites comprising the Southern Hemisphere Additional Ozonesondes (SHADOZ) network. The period covered is 1998-2000. Observations were made over: Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. Campaign data were collected on a Trans-Atlantic oceanographic cruise and during SAFARI-2000 in Zambia. The ozone data, with simultaneous temperature profiles to approx. 7 hPa and relative humidity to approx. 200 hPa, reside at: http://code9l6.gsfc.nasa.gov/ Data-services/shadoz. SHADOZ ozone time-series and profiles give a perspective on tropical total, stratospheric and tropospheric ozone in 1998-2000. Prominent features are highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Tropospheric ozone variability over the Indian and Pacific Ocean displays influences of the Indian Ocean Dipole, and convective mixing. Pollution transport from Africa, South American and the Maritime Continent is a seasonal feature. Tropospheric ozone seasonality over the Atlantic Basin shows effects of regional subsidence and recirculation as well as biomass burning. Dynamical and chemical influences appear to be of comparable magnitude though model studies are needed to quantify this.

Tropical Tropospheric Ozone from SHADOZ (Southern Hemisphere ADditional Ozonesondes) Network: A Project for Satellite Research, Process Studies, Education

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Schmidlin, Francis J.; Coetzee, G. J. R.; Hoegger, Bruno; Kirchhoff, V. W. J. H.; Ogawa, Toshihiro; Kawakami, Shuji; Posny, Francoise

2002-01-01

The first climatological overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropical and subtropics is based on ozone sounding data from 10 sites comprising the Southern Hemisphere Additional OZonesondes (SHADOZ) network. The period covered is 1998-2000. Observations were made over: Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. Campaign data were collected on a trans-Atlantic oceanographic cruise and during SAFARI-2000 in Zambia. The ozone data, with simultaneous temperature profiles to approx. 7 hPa and relative humidity to approx. 200 hPa, reside at: . SHADOZ ozone time-series and profiles give a perspective on tropical total, stratospheric and tropospheric ozone. Prominent features are highly variable tropospheric ozone and a zonal wave-one pattern in total (and tropospheric) column ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Tropospheric ozone variability over the Indian and Pacific Ocean displays influences of the Indian Ocean Dipole and convective mixing. Pollution transport from Africa and South America is a seasonal feature. Tropospheric ozone seasonality over the Atlantic Basin shows effects of regional subsidence and recirculation as well as biomass burning. Dynamical and chemical influences appear to be of comparable magnitude though model studies are needed to quantify this.

Analysis of European ozone trends in the period 1995-2014

NASA Astrophysics Data System (ADS)

Yan, Yingying; Pozzer, Andrea; Ojha, Narendra; Lin, Jintai; Lelieveld, Jos

2018-04-01

Surface-based measurements from the EMEP and Airbase networks are used to estimate the changes in surface ozone levels during the 1995-2014 period over Europe. We find significant ozone enhancements (0.20-0.59 µg m-3 yr-1 for the annual means; P-value < 0.01 according to an F-test) over the European suburban and urban stations during 1995-2012 based on the Airbase sites. For European background ozone observed at EMEP sites, it is shown that a significantly decreasing trend in the 95th percentile ozone concentrations has occurred, especially at noon (0.9 µg m-3 yr-1; P-value < 0.01), while the 5th percentile ozone concentrations continued to increase with a trend of 0.3 µg m-3 yr-1 (P-value < 0.01) during the study period. With the help of numerical simulations performed with the global chemistry-climate model EMAC, the importance of anthropogenic emissions changes in determining these changes over background sites are investigated. The EMAC model is found to successfully capture the observed temporal variability in mean ozone concentrations, as well as the contrast in the trends of 95th and 5th percentile ozone over Europe. Sensitivity simulations and statistical analysis show that a decrease in European anthropogenic emissions had contrasting effects on surface ozone trends between the 95th and 5th percentile levels and that background ozone levels have been influenced by hemispheric transport, while climate variability generally regulated the inter-annual variations of surface ozone in Europe.

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.; Briehl, D.

1978-01-01

Recently, passengers and crew members on long-distance commercial flights have filed complaints after suffering symptoms of ozone sickness. Studies were conducted to determine the frequency and concentration of ozone in commercial jet transports. The airliner problem with ozone prompted NASA to determine the ozone concentrations that might be encountered in the cabin of a small business jet. Simultaneous measurements of atmospheric ozone levels and ozone levels in the cabins of jet aircraft were necessary because of the wide and rapid variability of atmospheric ozone in flight. It was found that the atmospheric ozone concentrations in the case of B-747 airliners vary widely during a flight. A constant difference, or ratio, between ozone concentrations outside and inside the cabin does not exist.

Assessing the impact of local meteorological variables on surface ozone in Hong Kong during 2000-2015 using quantile and multiple line regression models

NASA Astrophysics Data System (ADS)

Zhao, Wei; Fan, Shaojia; Guo, Hai; Gao, Bo; Sun, Jiaren; Chen, Laiguo

2016-11-01

The quantile regression (QR) method has been increasingly introduced to atmospheric environmental studies to explore the non-linear relationship between local meteorological conditions and ozone mixing ratios. In this study, we applied QR for the first time, together with multiple linear regression (MLR), to analyze the dominant meteorological parameters influencing the mean, 10th percentile, 90th percentile and 99th percentile of maximum daily 8-h average (MDA8) ozone concentrations in 2000-2015 in Hong Kong. The dominance analysis (DA) was used to assess the relative importance of meteorological variables in the regression models. Results showed that the MLR models worked better at suburban and rural sites than at urban sites, and worked better in winter than in summer. QR models performed better in summer for 99th and 90th percentiles and performed better in autumn and winter for 10th percentile. And QR models also performed better in suburban and rural areas for 10th percentile. The top 3 dominant variables associated with MDA8 ozone concentrations, changing with seasons and regions, were frequently associated with the six meteorological parameters: boundary layer height, humidity, wind direction, surface solar radiation, total cloud cover and sea level pressure. Temperature rarely became a significant variable in any season, which could partly explain the peak of monthly average ozone concentrations in October in Hong Kong. And we found the effect of solar radiation would be enhanced during extremely ozone pollution episodes (i.e., the 99th percentile). Finally, meteorological effects on MDA8 ozone had no significant changes before and after the 2010 Asian Games.

Acute pulmonary function response to ozone in young adults as a function of body mass index

EPA Science Inventory

Recent studies have shown enhanced responsiveness to ozone in obese mice. Adiposity has not been examined as a possible modulator of ozone response in humans. We therefore examined the relationship between body mass index and the acute spirometric response to ozone (O(3)) exposur...

Variability of Irreversible Poleward Transport in the Lower Stratosphere

NASA Technical Reports Server (NTRS)

Olsen, Mark; Douglass, Anne; Newman, Paul; Nash, Eric; Witte, Jacquelyn; Ziemke, Jerry

2011-01-01

The ascent and descent of the Brewer-Dobson circulation plays a large role in determining the distributions of many constituents in the extratropical lower stratosphere. However, relatively fast, quasi-horizontal transport out of the tropics and polar regions also significantly contribute to determining these distributions. The tropical tape recorder signal assures that there must be outflow from the tropics into the extratropical lower stratosphere. The phase of the quasi-biennial oscillation (QBO) and state of the polar vortex are known to modulate the transport from the tropical and polar regions, respectively. In this study we examine multiple years of ozone distributions in the extratropical lower stratosphere observed by the Aura Microwave Limb Sounder (MLS) and the Aura High Resolution Dynamic Limb Sounder (HIRDLS). The distributions are compared with analyses of irreversible, meridional isentropic transport. We show that there is considerable year-to-year seasonal variability in the amount of irreversible transport from the tropics, which is related to both the phase of the QBO and the state of the polar vortex. The reversibility of the transport is consistent with the number of observed breaking waves. The variability of the atmospheric index of refraction in the lower stratosphere is shown to be significantly correlated with the wave breaking and amount of irreversible transport. Finally, we will show that the seasonal extratropical stratosphere to troposphere transport of ozone can be substantially modulated by the amount of irreversible meridional transport in the lower stratosphere and we investigate how observable these differences are in data of tropospheric ozone.

Influence of the Bermuda High on interannual variability of summertime ozone in the Houston-Galveston-Brazoria region

NASA Astrophysics Data System (ADS)

Wang, Yuxuan; Jia, Beixi; Wang, Sing-Chun; Estes, Mark; Shen, Lu; Xie, Yuanyu

2016-12-01

The Bermuda High (BH) quasi-permanent pressure system is the key large-scale circulation pattern influencing summertime weather over the eastern and southern US. Here we developed a multiple linear regression (MLR) model to characterize the effect of the BH on year-to-year changes in monthly-mean maximum daily 8 h average (MDA8) ozone in the Houston-Galveston-Brazoria (HGB) metropolitan region during June, July, and August (JJA). The BH indicators include the longitude of the BH western edge (BH-Lon) and the BH intensity index (BHI) defined as the pressure gradient along its western edge. Both BH-Lon and BHI are selected by MLR as significant predictors (p < 0.05) of the interannual (1990-2015) variability of the HGB-mean ozone throughout JJA, while local-scale meridional wind speed is selected as an additional predictor for August only. Local-scale temperature and zonal wind speed are not identified as important factors for any summer month. The best-fit MLR model can explain 61-72 % of the interannual variability of the HGB-mean summertime ozone over 1990-2015 and shows good performance in cross-validation (R2 higher than 0.48). The BH-Lon is the most important factor, which alone explains 38-48 % of such variability. The location and strength of the Bermuda High appears to control whether or not low-ozone maritime air from the Gulf of Mexico can enter southeastern Texas and affect air quality. This mechanism also applies to other coastal urban regions along the Gulf Coast (e.g., New Orleans, LA, Mobile, AL, and Pensacola, FL), suggesting that the BH circulation pattern can affect surface ozone variability through a large portion of the Gulf Coast.

SHADOZ (Southern Hemisphere ADditional Ozonesondes): A Look at the First Three Years' (1998-2000) Tropospheric Ozone Data

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Bhartia, Pawan K. (Technical Monitor)

2001-01-01

The first climatological overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropical and subtropics is based on ozone sounding data from 10 sites comprising the Southern Hemisphere ADditional OZonesondes (SHADOZ) network. The period covered is 1998-2000. Observations were made over: Ascension Island; Nairobi, Kenya; Irene, South Africa; RCunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natai, Brazil. Campaign data were collected on a trans-Atlantic oceanographic cruise and during SAFARI-2000 in Zambia. The ozone data, with simultaneous temperature profiles to approx. 7 hPa and relative humidity to approx. 200 hPa, reside at an open archive: . SHADOZ ozone time-series and profiles give a perspective on tropical total, stratospheric and tropospheric ozone in 1998-2000. Prominent features are highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Tropospheric ozone variability over the Indian and Pacific Ocean displays influences of the Indian Ocean Dipole, ENSO, and Madden-Julian circulation on convective mixing. Pollution transport from Africa, South American and the Maritime Continent is a seasonal feature. Tropospheric ozone seasonality over the Atlantic Basin shows effects of regional subsidence and recirculation as well as biomass burning. Dynamical and chemical influences appear to be of comparable magnitude.

SHADOZ (Southern Hemisphere ADditional Ozonesondes}: What Have We Learned About Tropical Tropospheric Ozone from the First Three Years (1998-2000) Data

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Bhartia, P. K. (Technical Monitor)

2002-01-01

The first climatological overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropical and subtropics is based on ozone sounding data from 10 sites comprising the Southern Hemisphere Additional OZonesondes (SHADOZ) network. The period covered is 1998-2000. Observations were made over: Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. Campaign data were collected on an Trans-Atlantic oceanographic cruise and during SAFARI-2000 in Zambia. The ozone data, with simultaneous temperature profiles to approximately 7 hPa and relative humidity to approximately 200 hPa, reside at: . SHADOZ ozone time-series and profiles give a perspective on tropical total, stratospheric and tropospheric ozone in 1998-2000. Prominent features are highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Tropospheric ozone variability over the Indian and Pacific Ocean displays influences of the Indian Ocean Dipole, and convective mixing. Pollution transport from Africa, South American and the Maritime Continent is a seasonal feature. Tropospheric ozone seasonality over the Atlantic Basin shows effects of regional subsidence and recirculation as well as biomass burning. Dynamical and chemical influences appear to be of comparable magnitude though model studies are needed to quantify this.

SHADOZ (Southern Hemisphere ADditional Ozonesondes): What Have We Learned About Tropical Tropospheric Ozone from the First Three Years' (1998-2000) Data?

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Bhartia, Pawan (Technical Monitor)

2002-01-01

The first climatological overview of total, stratospheric and tropospheric ozone in the southern hemisphere tropical and subtropics is based on ozone sounding data from 10 sites comprising the Southern Hemisphere Additional OZonesondes (SHADOZ) network. The period covered is 1998-2000. Observations were made over: Ascension Island; Nairobi, Kenya; Irene, South Africa; RCunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. Campaign data were collected on a trans-Atlantic oceanographic cruise and during SAFARI-2000 in Zambia. The ozone data, with simultaneous temperature profiles to approx. 7 hPa and relative humidity to approx. 200 hPa, reside at: . SHADOZ ozone time-series and profiles give a perspective on tropical total, stratospheric and tropospheric ozone in 1998-2000. Prominent features are highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Tropospheric ozone variability over the Indian and Pacific Ocean displays influences of the Indian Ocean Dipole, and convective mixing. Pollution transport from Africa, South American and the Maritime Continent is a seasonal feature. Tropospheric ozone seasonality over the Atlantic Basin shows effects of regional subsidence and recirculation as well as biomass burning. Dynamical and chemical influences appear to be of comparable magnitude though model studies are needed to quantify this.

Recent Changes in Tropospheric Ozone in the Tropics

NASA Technical Reports Server (NTRS)

Chandra, S.; Ziemke, J. R.; Einaudi, Franco (Technical Monitor)

2000-01-01

This paper presents a detailed characterization of tropical tropospheric column ozone variability on time scales varying from a few days to a solar cycle. The study is based on more than 20 years (1979 to the present) of tropospheric column ozone time series derived from the convective cloud differential (CCD) method using total ozone mapping spectrometer (TOMS) data. Results indicate three distinct regions in the tropics with distinctly three different zonal characteristics related to seasonal, interannual and solar variabilities. These three regions are the eastern Pacific, Atlantic, and western Pacific. Tropospheric column ozone in the Atlantic region peaks at about the same time (September-October) from 20 N to 20 S. The amplitude of the annual cycle, however, varies from about 3 to 6 Dobson unit (DU) from north to south of the equator. In comparison, the annual cycle in both the eastern and western Pacific is generally week and the phase varies from peak values in March and April in the northern hemisphere to September and October in the southern hemisphere. The interannual pattern in the three regions are also very different. The Atlantic region indicates a quasi biennial oscillation in the tropospheric column ozone which is out of phase with the stratospheric ozone. This is consistent with the photochemical control of this region caused by high pollution and high concentration of ozone producing precursors. The observed pattern, however, does not seem to be related to the interannual variability in ozone precursors related to biomass burning. Instead, it appears to be a manifestation of the UV modulation of upper tropospheric chemistry on a QBO time scale caused by stratospheric ozone. During El Nino events, there is anomalously low ozone in the eastern Pacific and high values in the western Pacific indicating the effects of convectively driven transport. The observed increase of 10-20 DU in tropospheric column ozone in the Indonesian region in the western Pacific during the recent 1997-1998 El Nino was associated with large-scale forest fires which may have contributed 5-10 DU of the total increase.

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

PubMed

Xu, Jingxin; Zheng, Youfei; He, Yuhong; Wu, Rongjun; Mai, Boru; Kang, Hanqing

2016-01-01

Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2) = 0.85 & T2: R(2) = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2) of cumulative ozone uptake. At the regional level, dry matter loss in winter wheat would reach 50% under elevated ozone concentrations and reduced solar irradiance as determined in T1, and 30% under conditions as determined in T2. Results from this study suggest that a combination of elevated ozone concentrations and reduced solar irradiance could result in substantial dry matter loss in the Chinese wheat-growing regions.

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China

PubMed Central

Xu, Jingxin; Zheng, Youfei; He, Yuhong; Wu, Rongjun; Mai, Boru; Kang, Hanqing

2016-01-01

Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R2 = 0.85 & T2: R2 = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m-2 of cumulative ozone uptake. At the regional level, dry matter loss in winter wheat would reach 50% under elevated ozone concentrations and reduced solar irradiance as determined in T1, and 30% under conditions as determined in T2. Results from this study suggest that a combination of elevated ozone concentrations and reduced solar irradiance could result in substantial dry matter loss in the Chinese wheat-growing regions. PMID:26760509

Evaluation of the Ozone Fields in NASA's MERRA-2 Reanalysis

NASA Technical Reports Server (NTRS)

Wargan, Krzysztof; Pawson, Steven; Labow, Gordon; Frith, Stacey M.; Livesey, Nathaniel; Partyka, Gary

2017-01-01

The assimilated ozone product from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2), produced at NASAs Global Modeling and Assimilation Office (GMAO) is summarized. The reanalysis begins in 1980 with the use of retrieved partial-column ozone concentrations from a series of Solar Backscatter Ultraviolet Radiometer (SBUV) instruments on NASA and NOAA spacecraft. Beginning in October 2004, retrieved ozone profiles from the Microwave Limb Sounder (MLS) and total column ozone from the Ozone Monitoring Instrument (OMI) on NASAs EOS Aura satellite are assimilated. While this change in data streams does lead to a discontinuity in the assimilated ozone fields in MERRA-2, making it not useful for studies in decadal (secular) trends in ozone, this choice was made to prioritize demonstrating the value NASAs high-quality research data in the reanalysis context. The MERRA-2 ozone is compared with independent satellite and ozonesonde data, focusing on the representation of the spatial and temporal variability of stratospheric and upper-tropospheric ozone. The comparisons show agreement within 10 (standard deviation of the difference) between MERRA-2 profiles and independent satellite data in most of the stratosphere. The agreement improves after 2004, when EOS Aura data are assimilated. The standard deviation of the differences between the lower-stratospheric and upper-tropospheric MERRA-2 ozone and ozonesondes is 11.2 and 24.5, respectively, with correlations of 0.8 and above. This is indicative of a realistic representation of the UTLS ozone variability in MERRA-2. After 2004, the upper tropospheric ozone in MERRA-2 shows a low bias compared to the sondes, but the covariance with independent observations is improved compared to earlier years. Case studies demonstrate the integrity of MERRA-2 analyses in representing important features such as tropopause folds.

Impact of Surface Emissions to the Zonal Variability of Tropical Tropospheric Ozone and Carbon Monoxide for November 2004

NASA Technical Reports Server (NTRS)

Bowman, K. W.; Jones, D.; Logan, J.; Worden, H.; Boersma, F.; Chang, R.; Kulawik, S.; Osterman, G.; Worden, J.

2008-01-01

The chemical and dynamical processes governing the zonal variability of tropical tropospheric ozone and carbon monoxide are investigated for November 2004 using satellite observations, in-situ measurements, and chemical transport models in conjunction with inverse-estimated surface emissions. Vertical ozone profile estimates from the Tropospheric Emission Spectrometer (TES) and ozone sonde measurements from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network show the so called zonal 'wave-one' pattern, which is characterized by peak ozone concentrations (70-80 ppb) centered over the Atlantic, as well as elevated concentrations of ozone over Indonesia and Australia (60-70 ppb) in the lower troposphere. Observational evidence from TES CO vertical profiles and Ozone Monitoring Instrument (OMI) NO2 columns point to regional surface emissions as an important contributor to the elevated ozone over Indonesia. This contribution is investigated with the GEOS-Chem chemistry and transport model using surface emission estimates derived from an optimal inverse model, which was constrained by TES and Measurements Of Pollution In The Troposphere (MOPITT) CO profiles (Jones et al., 2007). These a posteriori estimates, which were over a factor of 2 greater than climatological emissions, reduced differences between GEOS-Chem and TES ozone observations by 30-40% and led to changes in GEOS-Chem upper tropospheric ozone of up to 40% over Indonesia. The remaining residual differences can be explained in part by upper tropospheric ozone produced from lightning NOx in the South Atlantic. Furthermore, model simulations from GEOS-Chem indicate that ozone over Indonesian/Australian is more sensitive to changes in surface emissions of NOx than ozone over the tropical Atlantic.

Regional and hemispheric influences on temporal variability in baseline carbon monoxide and ozone over the Northeast US

EPA Science Inventory

Interannual variability in baseline carbon monoxide (CO) and ozone (O3), defined as mixing ratios under minimal influence of recent and local emissions, was studied for seven rural sites in the Northeast US over 2001–2010. Annual baseline CO exhibited statistically signific...

Ozone Climatology for Portsmouth, NH 1978-2002

NASA Astrophysics Data System (ADS)

Wake, C. P.; Miller, S. T.

2003-12-01

Hourly ozone mixing ratios have been monitored in Portsmouth, NH since 1978 for the typical "summer" ozone season (April to October) by the New Hampshire Department of Environmental Services. This 25 year record provides the basis to investigate seasonal variability in daily summertime ozone levels in Portsmouth NH and evaluate the relationship between ozone mixing ratios, temperature, precipitation, and the state of El Niño/Southern Oscillation. The overall goal of this research is to identify significant relationships between high ozone days and a suite of climate variables. The mean daily ozone mixing ratio in Portsmouth from 1977 through 2002 was 40 ppbv (sd 17 ppbv) with a mean of 6 days per summer when maxiumum 8 hour ozone levels exceed the 80 ppbv level. The highest ozone levels usually occur during June, July and August (with a peak in July), but high ozone days also occur May and September. April and October rarely experience high ozone. High ozone in coastal New Hampshire (and for most of New England) occurs predominantly on days when maximum temperatures are above 85 oF, although there are also may hot days when ozone levels do not reach elevated levels. Analysis of the relationship between number of days per year when 8 hour ozone is greater than 80 ppbv and maximum temperatures are greater than 85 oF indicates that there is a positive correlation (r = 0.60). Surprisingly, there is not a strong inverse relationship between ozone days and precipitation. For example, over the last 25 years, 1988 clearly stands out with 20 days with maximum 8 hour ozone above 80 ppbv. However, 1988 also experienced considerable precipitation in July and August (14.1 inches compared to the climatological mean of 6.7 inches) and relatively few days without precipitation (38 compared to the climatological mean of 44). There are differences in temperature, precipitation, and ozone levels in Portsmouth during years that are classified as El Ni¤o and neutral, compared to La Nina years. However, we have only experienced one strong La Nina year in the past 25 years, so the results must be viewed with caution. The La Nina year (1988) experience high ozone and more frequent hot days, as well as double the average precipitation. El Niño years experience slightly warmer, dryer and experience more frequent ozone days, although they are not significantly different from neutral years. Our results indicate that hot summers are indeed related to higher than average ozone levels, although there is considerable variability in this relationship. There does not appear to be a consistent ozone - precipitation relationship. Further work is needed to define these relationships for a larger number of stations throughout New England and also for comparison to broader synoptic to hemispheric circulation patterns and sea surface temperatures.

Influence of altitude on ozone levels and variability in the lower troposphere: a ground-based study for western Europe over the period 2001-2004

NASA Astrophysics Data System (ADS)

Chevalier, A.; Gheusi, F.; Delmas, R.; Ordóñez, C.; Sarrat, C.; Zbinden, R.; Thouret, V.; Athier, G.; Cousin, J.-M.

2007-08-01

The PAES (French acronym for synoptic scale atmospheric pollution) network focuses on the chemical composition (ozone, CO, NOx/y and aerosols) of the lower troposphere (0-3000 m). Its high-altitude surface stations located in different mountainous areas in France complete the low-altitude rural MERA stations (the French contribution to the european program EMEP, European Monitoring and Evaluation Program). They are representative of pollution at the scale of the French territory because they are away from any major source of pollution. This study deals with ozone observations between 2001 and 2004 at 11 stations from PAES and MERA, in addition to 16 elevated stations located in mountainous areas of Switzerland, Germany, Austria, Italy and Spain. The set of stations covers a range of altitudes between 115 and 3550 m. The comparison between recent ozone mixing ratios to those of the last decade at Pic du Midi (2877 m), as well as trends calculated over 14-year data series at three high-altitude sites in the Alps (Jungfraujoch, Sonnblick and Zugspitze) reveal that ozone is still increasing but at a slower rate than in the 1980s and 1990s. The 2001-2004 mean levels of ozone from surface stations capture the ozone stratification revealed by climatological profiles from the airborne observation system MOZAIC (Measurement of OZone and water vapour by Airbus In-service airCraft) and from ozone soundings above Payerne (Switzerland). In particular all data evidence a clear transition at about 1000-1200 m a.s.l. between a sharp gradient below (of the order of +30 ppb/km) and a gentler gradient (+3 ppb/km) above. The same altitude (1200 m) is also found to be a threshold regarding how well the ozone levels at the surface stations agree with the free-tropospheric reference (MOZAIC or soundings). Below the departure can be as large as 40%, but suddenly drops within 15% above. For stations above 2000 m, the departure is even less than 8%. Ozone variability also reveals a clear transition between boundary-layer and free-tropospheric regimes around 1000 m a.s.l. Below, diurnal photochemistry accounts for about the third of the variability in summer, but less than 20% above - and at all levels in winter - where ozone variability is mostly due to day-to-day changes (linked to weather conditions or synoptic transport). In summary, the altitude range 1000-1200 m clearly turns out in our study to be an upper limit below which specific surface effects dominate the ozone content. Monthly-mean ozone mixing-ratios show at all levels a minimum in winter and the classical summer broad maximum in spring and summer - which is actually the superposition of the tropospheric spring maximum (April-May) and regional pollution episodes linked to persistent anticyclonic conditions that may occur from June to September. To complement this classical result it is shown that summer maxima are associated with considerably more variability than the spring maximum. This ensemble of findings support the relevance of mountain station networks such as PAES for the long-term observation of free-tropospheric ozone over Europe.

A statistical probe into variability within total ozone time series over Arosa, Switzerland (9.68°E, 46.78°N)

NASA Astrophysics Data System (ADS)

Chakraborthy, Parthasarathi; Chattopadhyay, Surajit

2013-02-01

Endeavor of the present paper is to investigate the statistical properties of the total ozone concentration time series over Arosa, Switzerland (9.68°E, 46.78°N). For this purpose, different statistical data analysis procedures have been employed for analyzing the mean monthly total ozone concentration data, collected over a period of 40 years (1932-1971), at the above location. Based on the computations on the available data set, the study reports different degrees of variations in different months. The month of July is reported as the month of lowest variability. April and May are found to be the most correlated months with respect to total ozone concentration.

Analysis of Ozone in Cloudy Versus Clear Sky Conditions

NASA Technical Reports Server (NTRS)

Strode, Sarah; Douglass, Anne; Ziemke, Jerald

2016-01-01

Convection impacts ozone concentrations by transporting ozone vertically and by lofting ozone precursors from the surface, while the clouds and lighting associated with convection affect ozone chemistry. Observations of the above-cloud ozone column (Ziemke et al., 2009) derived from the OMI instrument show geographic variability, and comparison of the above-cloud ozone with all-sky tropospheric ozone columns from OMI indicates important regional differences. We use two global models of atmospheric chemistry, the GMI chemical transport model (CTM) and the GEOS-5 chemistry climate model, to diagnose the contributions of transport and chemistry to observed differences in ozone between areas with and without deep convection, as well as differences in clean versus polluted convective regions. We also investigate how the above-cloud tropospheric ozone from OMI can provide constraints on the relationship between ozone and convection in a free-running climate simulation as well as a CTM.

Seasonal and Interannual Variabilities in Tropical Tropospheric Ozone

NASA Technical Reports Server (NTRS)

Ziemke, J. R.; Chandra, S.

1999-01-01

This paper presents a detailed characterization of seasonal and interannual variability in tropical tropospheric column ozone (TCO). TCO time series are derived from 20 years (1979-1998) of total ozone mapping spectrometer (TOMS) data using the convective cloud differential (CCD) method. Our study identifies three regions in the tropics with distinctly different zonal characteristics related to seasonal and interannual variability. These three regions are the eastern Pacific, Atlantic, and western Pacific. Results show that in both the eastern and western Pacific seasonal-cycle variability of northern hemisphere (NH) TCO exhibits maximum amount during NH spring whereas largest amount in southern hemisphere (SH) TCO occurs during SH spring. In the Atlantic, maximum TCO in both hemispheres occurs in SH spring. These seasonal cycles are shown to be comparable to seasonal cycles present in ground-based ozonesonde measurements. Interannual variability in the Atlantic region indicates a quasi-biennial oscillation (QBO) signal that is out of phase with the QBO present in stratospheric column ozone (SCO). This is consistent with high pollution and high concentrations of mid-to-upper tropospheric O3-producing precursors in this region. The out of phase relation suggests a UV modulation of tropospheric photochemistry caused by the QBO in stratospheric O3. During El Nino events there is anomalously low TCO in the eastern Pacific and high values in the western Pacific, indicating the effects of convectively-driven transport of low-value boundary layer O3 (reducing TCO) and O3 precursors including H2O and OH. A simplified technique is proposed to derive high-resolution maps of TCO in the tropics even in the absence of tropopause-level clouds. This promising approach requires only total ozone gridded measurements and utilizes the small variability observed in TCO near the dateline. This technique has an advantage compared to the CCD method because the latter requires high-resolution footprint measurements of both reflectivity and total ozone in the presence of tropopause-level cloud tops.

On the Size of the Antarctic Ozone Hole

NASA Technical Reports Server (NTRS)

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

2002-01-01

The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million sq km. In the 8-year period from 1981 to 1989, the area expanded by 18 Million sq km. During the last 5 years, the hole has been observed to exceed 25 Million sq km over brief periods. In the spring of 2002, the size of the ozone hole barely reached 20 Million sq km for only a couple of days. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre-1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

A Hybrid Model for Spatially and Temporally Resolved Ozone Exposures in the Continental United States

PubMed Central

Di, Qian; Rowland, Sebastian; Koutrakis, Petros; Schwartz, Joel

2017-01-01

Ground-level ozone is an important atmospheric oxidant, which exhibits considerable spatial and temporal variability in its concentration level. Existing modeling approaches for ground-level ozone include chemical transport models, land-use regression, Kriging, and data fusion of chemical transport models with monitoring data. Each of these methods has both strengths and weaknesses. Combining those complementary approaches could improve model performance. Meanwhile, satellite-based total column ozone, combined with ozone vertical profile, is another potential input. We propose a hybrid model that integrates the above variables to achieve spatially and temporally resolved exposure assessments for ground-level ozone. We used a neural network for its capacity to model interactions and nonlinearity. Convolutional layers, which use convolution kernels to aggregate nearby information, were added to the neural network to account for spatial and temporal autocorrelation. We trained the model with AQS 8-hour daily maximum ozone in the continental United States from 2000 to 2012 and tested it with left out monitoring sites. Cross-validated R2 on the left out monitoring sites ranged from 0.74 to 0.80 (mean 0.76) for predictions on 1 km×1 km grid cells, which indicates good model performance. Model performance remains good even at low ozone concentrations. The prediction results facilitate epidemiological studies to assess the health effect of ozone in the long term and the short term. PMID:27332675

The numerical modeling the sensitivity of coastal wind and ozone concentration to different SST forcing

NASA Astrophysics Data System (ADS)

Choi, Hyun-Jung; Lee, Hwa Woon; Jeon, Won-Bae; Lee, Soon-Hwan

2012-01-01

This study evaluated an atmospheric and air quality model of the spatial variability in low-level coastal winds and ozone concentration, which are affected by sea surface temperature (SST) forcing with different thermal gradients. Several numerical experiments examined the effect of sea surface SST forcing on the coastal atmosphere and air quality. In this study, the RAMS-CAMx model was used to estimate the sensitivity to two different resolutions of SST forcing during the episode day as well as to simulate the low-level coastal winds and ozone concentration over a complex coastal area. The regional model reproduced the qualitative effect of SST forcing and thermal gradients on the coastal flow. The high-resolution SST derived from NGSST-O (New Generation Sea Surface Temperature Open Ocean) forcing to resolve the warm SST appeared to enhance the mean response of low-level winds to coastal regions. These wind variations have important implications for coastal air quality. A higher ozone concentration was forecasted when SST data with a high resolution was used with the appropriate limitation of temperature, regional wind circulation, vertical mixing height and nocturnal boundary layer (NBL) near coastal areas.

Simulated sensitivity of seasonal ozone exposure in the Great Lakes region to changes in anthropogenic emissions in the presence of interannual variability

Treesearch

Jerome D. Fast; Warren E. Heilman

2005-01-01

A coupled meteorological and chemical modeling system with a 12-km horizontal grid spacing was used to simulate the evolution of ozone over the Great Lakes region between May and September of 1999 and 2001. The overall temporal and spatial variations in hourly ozone concentrations and ozone exposure from control simulations agreed reasonably well with the observations...

What Controls the Size of the Antarctic Ozone Hole?

NASA Technical Reports Server (NTRS)

Bhartia, P. K. (Technical Monitor); Newman, Paul A.; Kawa, S. Randolph; Nash, Eric R.

2002-01-01

The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million square kilometers. In the 8-year period from 1981 to 1989, the area expanded by 18 Million square kilometers. During the last 5 years, the hole has been observed to exceed 25 Million square kilometers over brief periods. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre- 1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

Evaluation of the Ozone Fields in NASA's MERRA-2 Reanalysis

NASA Technical Reports Server (NTRS)

Wargan, Krzysztof; Labow, Gordon; Frith, Stacey; Pawson, Steven; Livesey, Nathaniel; Partyka, Gary

2017-01-01

We describe and assess the quality of the assimilated ozone product from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) produced at NASAs Global Modeling and Assimilation Office (GMAO) spanning the time period from 1980 to present. MERRA-2 assimilates partial column ozone retrievals from a series of Solar Backscatter Ultraviolet (SBUV) radiometers on NASA and NOAA spacecraft between January 1980 and September 2004; starting in October 2004 retrieved ozone profiles from the Microwave Limb Sounder (MLS) and total column ozone from the Ozone Monitoring Instrument on NASAs EOS Aura satellite are assimilated. We compare the MERRA-2 ozone with independent satellite and ozonesonde data focusing on the representation of the spatial and temporal variability of stratospheric and upper tropospheric ozone and on implications of the change in the observing system from SBUV to EOS Aura. The comparisons show agreement within 10 (standard deviation of the difference) between MERRA-2 profiles and independent satellite data in most of the stratosphere. The agreement improves after 2004 when EOS Aura data are assimilated. The standard deviation of the differences between the lower stratospheric and upper tropospheric MERRA-2 ozone and ozonesondes is 11.2 and 24.5, respectively, with correlations of 0.8 and above, indicative of a realistic representation of the near-tropopause ozone variability in MERRA-2. The agreement improves significantly in the EOS Aura period, however MERRA-2 is biased low in the upper troposphere with respect to the ozonesondes. Caution is recommended when using MERRA-2 ozone for decadal changes and trend studies.

Evaluation of the Ozone Fields in NASA’s MERRA-2 Reanalysis

PubMed Central

Wargan, Krzysztof; Labow, Gordon; Frith, Stacey; Pawson, Steven; Livesey, Nathaniel; Partyka, Gary

2018-01-01

We describe and assess the quality of the assimilated ozone product from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) produced at NASA’s Global Modeling and Assimilation Office (GMAO) spanning the time period from 1980 to present. MERRA-2 assimilates partial column ozone retrievals from a series of Solar Backscatter Ultraviolet (SBUV) radiometers on NASA and NOAA spacecraft between January 1980 and September 2004; starting in October 2004 retrieved ozone profiles from the Microwave Limb Sounder (MLS) and total column ozone from the Ozone Monitoring Instrument on NASA’s EOS Aura satellite are assimilated. We compare the MERRA-2 ozone with independent satellite and ozonesonde data focusing on the representation of the spatial and temporal variability of stratospheric and upper tropospheric ozone and on implications of the change in the observing system from SBUV to EOS Aura. The comparisons show agreement within 10 % (standard deviation of the difference) between MERRA-2 profiles and independent satellite data in most of the stratosphere. The agreement improves after 2004 when EOS Aura data are assimilated. The standard deviation of the differences between the lower stratospheric and upper tropospheric MERRA-2 ozone and ozonesondes is 11.2 % and 24.5 %, respectively, with correlations of 0.8 and above, indicative of a realistic representation of the near-tropopause ozone variability in MERRA-2. The agreement improves significantly in the EOS Aura period, however MERRA-2 is biased low in the upper troposphere with respect to the ozonesondes. Caution is recommended when using MERRA-2 ozone for decadal changes and trend studies. PMID:29527096

Evaluation of the Ozone Fields in NASA's MERRA-2 Reanalysis.

PubMed

Wargan, Krzysztof; Labow, Gordon; Frith, Stacey; Pawson, Steven; Livesey, Nathaniel; Partyka, Gary

2017-04-01

We describe and assess the quality of the assimilated ozone product from the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) produced at NASA's Global Modeling and Assimilation Office (GMAO) spanning the time period from 1980 to present. MERRA-2 assimilates partial column ozone retrievals from a series of Solar Backscatter Ultraviolet (SBUV) radiometers on NASA and NOAA spacecraft between January 1980 and September 2004; starting in October 2004 retrieved ozone profiles from the Microwave Limb Sounder (MLS) and total column ozone from the Ozone Monitoring Instrument on NASA's EOS Aura satellite are assimilated. We compare the MERRA-2 ozone with independent satellite and ozonesonde data focusing on the representation of the spatial and temporal variability of stratospheric and upper tropospheric ozone and on implications of the change in the observing system from SBUV to EOS Aura. The comparisons show agreement within 10 % (standard deviation of the difference) between MERRA-2 profiles and independent satellite data in most of the stratosphere. The agreement improves after 2004 when EOS Aura data are assimilated. The standard deviation of the differences between the lower stratospheric and upper tropospheric MERRA-2 ozone and ozonesondes is 11.2 % and 24.5 %, respectively, with correlations of 0.8 and above, indicative of a realistic representation of the near-tropopause ozone variability in MERRA-2. The agreement improves significantly in the EOS Aura period, however MERRA-2 is biased low in the upper troposphere with respect to the ozonesondes. Caution is recommended when using MERRA-2 ozone for decadal changes and trend studies.

Global QBO in circulation and ozone. Part 1: Reexamination of observational evidence

NASA Technical Reports Server (NTRS)

Tung, K. K.; Yang, H.

1994-01-01

Observational evidence for a global quasi-biennial oscillation (QBO) pattern is reviewed. In particular, the presence of an extratropical, as well as an equatorial, component of the QBO signal in column ozone is established. It is found that the ozone interannual variability is such that as one moves away from the Tropics, the frequency spectrum of the anomaly changes from one that is dominated by the equatorial QBO frequency of 1/30 mo to a two-peak spectrum around the two frequencies: 1/30 mo and 1/20 mo. Instead of treating the 1/20 mo frequency as a separate phenomenon to be filtered away in extracting the QBO in the extratropics, as was previously done, the authors argue that both peaks are integral parts of the extratropical QBO phenomenon. The 1/20 mo frequency happens to be the difference combination of the QBO frequency 1/30 mo and the annual frequency 1/12 mo. Therefore, it can represent the result of the QBO modulating an annual cycle. The authors suggest that previous methods of extracting the extratropical QBO signal severely underestimated the contribution of the QBO to the interannual variability of ozone when data are filtered to pass only the component with the period of equatorial QBO. Further, it is argued that the transport of equatorial QBO ozone anomaly by a non-QBO circulation can at most account for 6-8 Dobson units (DU) of the observed interannual variability of column ozone in the extratropics. The remaining variability (up to 20 DU) probably cannot be produced without an anomaly in the transporting circulation in the extratropics.

Turbulent transport and production/destruction of ozone in a boundary layer over complex terrain

NASA Technical Reports Server (NTRS)

Greenhut, Gary K.; Jochum, Anne M.; Neininger, Bruno

1994-01-01

The first Intensive Observation Period (IOP) of the Swiss air pollution experiment POLLUMET took place in 1990 in the Aare River Valley between Bern and Zurich. During the IOP, fast response measurements of meteorological variables and ozone concentration were made within the boundary layer aboard a motorglider. In addition, mean values of meteorological variables and the concentrations of ozone and other trace species were measured using other aircraft, pilot balloons, tethersondes, and ground stations. Turbulent flux profiles of latent and sensible heat and ozone are calculated from the fast response data. Terms in the ozone mean concentration budget (time rate of change of mean concentration, horizontal advection, and flux divergence) are calculated for stationary time periods both before and after the passage of a cold front. The source/sink term is calculated as a residual in the budget, and its sign and magnitude are related to the measured concentrations of reactive trace species within the boundary layer. Relationships between concentration ratios of trace species and ozone concentration are determined in order to understand the influence of complex terrain on the processes that produce and destroy ozone.

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 95th percentile and summertime trends mainly due to effective control strategies. Based on the 5th percentile daytime ozone for C1 (strong southeasterly wind) in coastal sites, this study found that the cleanest air masses that Houston received became more polluted during the summer of 2000-2014 by 1-3 ppbv. Though this study focused on Houston, the analysis method presented could generally be used to estimate ozone trends in other regions where surface ozone is dominantly influenced by both wind patterns and local emissions.

On the variability of tropospheric ozone in the Tropical Eastern Pacific and its impact on the oxidizing capacity

NASA Astrophysics Data System (ADS)

Saiz-Lopez, A.; Gomez Martin, J.; Hay, T.; Mahajan, A.; Ordoñez, C.; Parrondo Sempere, M.; Gil, M. J.; Agama Reyes, M.; Paredes Mora, J.; Voemel, H.

2012-12-01

Observations of surface ozone, NOx and meteorological variables were made during two ground based field campaigns in the Eastern Pacific marine boundary layer (MBL). The first study was PIQUERO (Primera Investigación de la Química, Evolución y Reparto de Ozono), running from September 2000 to July 2001 in parallel to the Southern Hemisphere ADditional OZonesondes (SHADOZ) in the Galápagos Islands. The second study is the Climate and HAlogen Reactivity tropicaL EXperiment (CHARLEX), running from September 2010 to present. These long-term, high frequency, measurements enable a detailed description of the daily, monthly, seasonal and interannual variability of ozone and help to constrain the MBL and lower free troposphere (FT) ozone budget. In the Equatorial Eastern Pacific "cold season" (August - October), net ozone photochemical destruction of ~ 2 ppb day-1 occurs in the MBL (~30% due to halogens, and the rest to HOx). Ozone recovers by entrainment from aloft at night. The monthly baseline is set by the tropical instability waves (TIW), which also impact the ozone concentration in the lower FT. In the cold phase of the TIWs the MBL is stratified and, apart from higher surface ozone, it may also contain an upper drier layer with higher ozone between ~ 500 m and the main inversion at ~1 km. In the warm phase the buoyant MBL expands upwards (as much as 500 m) and poor ozone air reaches the FT. As the system shifts to the warm season (February- April), the TIWs stop and the sea becomes warmer, increasing evaporation and reducing ozone. The inversion is pushed upwards and finally disappears or becomes very weak. Surface ozone is so low that even at the low background NOx levels observed ozone production balances photochemical destruction, so the daily profile is flat (observed local effects in the populated areas of Galapagos are discussed). In February Galapagos is almost in the doldrums because the Inter-Tropical Convergence Zone (ITCZ) shifts south. In this situation, air convected at the ITZC is advected at different heights in the FT over Galapagos, so the entrainment of air from the FT does not replenish MBL ozone, explaining the low seasonal minimum. An important aspect of the marked ozone seasonal cycle is the impact on OH. levels. The consequences of this for the oxidizing capacity of the lower atmosphere are discussed.

Probabilistic Forecasting of Surface Ozone with a Novel Statistical Approach

NASA Technical Reports Server (NTRS)

Balashov, Nikolay V.; Thompson, Anne M.; Young, George S.

2017-01-01

The recent change in the Environmental Protection Agency's surface ozone regulation, lowering the surface ozone daily maximum 8-h average (MDA8) exceedance threshold from 75 to 70 ppbv, poses significant challenges to U.S. air quality (AQ) forecasters responsible for ozone MDA8 forecasts. The forecasters, supplied by only a few AQ model products, end up relying heavily on self-developed tools. To help U.S. AQ forecasters, this study explores a surface ozone MDA8 forecasting tool that is based solely on statistical methods and standard meteorological variables from the numerical weather prediction (NWP) models. The model combines the self-organizing map (SOM), which is a clustering technique, with a step wise weighted quadratic regression using meteorological variables as predictors for ozone MDA8. The SOM method identifies different weather regimes, to distinguish between various modes of ozone variability, and groups them according to similarity. In this way, when a regression is developed for a specific regime, data from the other regimes are also used, with weights that are based on their similarity to this specific regime. This approach, regression in SOM (REGiS), yields a distinct model for each regime taking into account both the training cases for that regime and other similar training cases. To produce probabilistic MDA8 ozone forecasts, REGiS weighs and combines all of the developed regression models on the basis of the weather patterns predicted by an NWP model. REGiS is evaluated over the San Joaquin Valley in California and the northeastern plains of Colorado. The results suggest that the model performs best when trained and adjusted separately for an individual AQ station and its corresponding meteorological site.

Trends from the Long-term Data Record and Models: What Do They Tell Us About our Ability to Predict Ozone Recovery?

NASA Technical Reports Server (NTRS)

Strahan, Susan; Stolarski, Richard; Douglass, Anne; Steenrod, Stephen

2005-01-01

Our industrial society has performed an experiment on the stratospheric ozone layer over the last several decades. The initial part of this experiment was the rapidly increasing release of halogen-containing compounds that carry chlorine and bromine to the stratosphere where they can cause a loss of ozone. The present part of this experiment is the implementation of the Montreal Protocol, which has led to a leveling off of these halogen compounds and the beginning of their slow removal from the atmosphere. The observation and attribution of ozone response to the halogens has been a particularly important and difficult task because of the impact of solar cycle uv variation, two major volcanic eruptions (El Chichon and Pinatubo), and interannual dynamic variability of the stratosphere. We have run 3 different simulations of the chemistry and transport of ozone and the minor constituents that affect ozone to help evaluate our understanding of the causes of ozone change and to assess our ability to predict ozone recovery with the removal of halogens from the stratosphere. One simulation, using the Goddard chemical transport model (CTM), had interannual variability in the dynamics for the entire 50 years of simulation, which included the past 3 decades (1974-2004) and the next 2 decades to 2022. The other two simulations used the Global Modeling Initiative (GMI) CTM with no dynamical variability: one used a the winds and temperatures from a repeating warm Arctic winter and the other used a repeating cold Arctic winter. All simulations included the effects of aerosol surfaces from volcanic eruptions on chemical reactions as well as the variation in UV over the 11-year solar cycle.

Lightning and Other Influences On Tropical Tropospheric Ozone: Empirical Studies of Covariation

NASA Technical Reports Server (NTRS)

Chatfield, Robert B.; Guan, Hong; Hudson, Robert D.; Witte, Jacquelyne C.

2003-01-01

Tropical and subtropical tropospheric ozone are important radiatively active species, with particularly large effects in the upper third of the troposphere. Temporal variability of O3 has proved difficult to simulate day by day in process models. Thus, individual roles of lightning, biomass burning, and other pollution in providing precursor NO(x), radicals, and chain carriers (CO, hydrocarbons) remain unquantified by simulation, and it is theoretically reasonable that individual roles are magnified by a joint synergy. We use wavelet analysis and Burg-algorithm maximum entropy spectral analyses to describe time-scales and correlation of ozone with proxies for processes controlling its concentration. Our empirical studies link time variations apparent in several datasets: the SHADOZ (Southern Hemisphere Additional Ozonesondes) network stations (Nairobi, Fiji), and auxiliary series with power to explain ozone-determining processes, with some interpretation based on the TTO (Tropical Tropospheric Ozone) product derived from TOMS (the Total Ozone Mapping Spectrometer). The auxiliary series are The OTD/LIS(Optical Transient Detector/Lightning Imaging Sensor) measurements of the lightning NO(x) source, the OLR (Outgoing Longwave Radiation)measurement of high-topped clouds, and standard meteorological variables from the United States NCEP (National Centers for Environmental Prediction) and Data Assimilation Office analyses. Concentrating on equatorial ozone, we compare the statistical evidence on the variability of tropospheric ozone. Important variations occur on approximately two-week, two-month (Madden-Julian Oscillation) and annual scales, and relations with OLR suggest controls associated with continental clouds. Hence we are now using the Lightning Imaging Sensor data set to indicate NO(x) sources. We report initial results defining relative roles of the process mentioned affecting O3 using their covariance properties.

Impacts of ozone air pollution and temperature extremes on crop yields: Spatial variability, adaptation and implications for future food security

NASA Astrophysics Data System (ADS)

Tai, Amos P. K.; Val Martin, Maria

2017-11-01

Ozone air pollution and climate change pose major threats to global crop production, with ramifications for future food security. Previous studies of ozone and warming impacts on crops typically do not account for the strong ozone-temperature correlation when interpreting crop-ozone or crop-temperature relationships, or the spatial variability of crop-to-ozone sensitivity arising from varietal and environmental differences, leading to potential biases in their estimated crop losses. Here we develop an empirical model, called the partial derivative-linear regression (PDLR) model, to estimate the spatial variations in the sensitivities of wheat, maize and soybean yields to ozone exposures and temperature extremes in the US and Europe using a composite of multidecadal datasets, fully correcting for ozone-temperature covariation. We find generally larger and more spatially varying sensitivities of all three crops to ozone exposures than are implied by experimentally derived concentration-response functions used in most previous studies. Stronger ozone tolerance is found in regions with high ozone levels and high consumptive crop water use, reflecting the existence of spatial adaptation and effect of water constraints. The spatially varying sensitivities to temperature extremes also indicate stronger heat tolerance in crops grown in warmer regions. The spatial adaptation of crops to ozone and temperature we find can serve as a surrogate for future adaptation. Using the PDLR-derived sensitivities and 2000-2050 ozone and temperature projections by the Community Earth System Model, we estimate that future warming and unmitigated ozone pollution can combine to cause an average decline in US wheat, maize and soybean production by 13%, 43% and 28%, respectively, and a smaller decline for European crops. Aggressive ozone regulation is shown to offset such decline to various extents, especially for wheat. Our findings demonstrate the importance of considering ozone regulation as well as ozone and climate change adaptation (e.g., selecting heat- and ozone-tolerant cultivars, irrigation) as possible strategies to enhance future food security in response to imminent environmental threats.

Medical ozone increases methotrexate clinical response and improves cellular redox balance in patients with rheumatoid arthritis.

PubMed

León Fernández, Olga Sonia; Viebahn-Haensler, Renate; Cabreja, Gilberto López; Espinosa, Irainis Serrano; Matos, Yanet Hernández; Roche, Liván Delgado; Santos, Beatriz Tamargo; Oru, Gabriel Takon; Polo Vega, Juan Carlos

2016-10-15

Medical ozone reduced inflammation, IL-1β, TNF-α mRNA levels and oxidative stress in PG/PS-induced arthritis in rats. The aim of this study was to investigate the medical ozone effects in patients with rheumatoid arthritis treated with methotrexate and methotrexate+ozone, and to compare between them. A randomized clinical study with 60 patients was performed, who were divided into two groups: one (n=30) treated with methotrexate (MTX), folic acid and Ibuprophen (MTX group) and the second group (n=30) received the same as the MTX group+medical ozone by rectal insufflation of the gas (MTX+ozone group). The clinical response of the patients was evaluated by comparing Disease Activity Score 28 (DAS28), Health Assessment Questionnaire Disability Index (HAQ-DI), Anti-Cyclic Citrullinated (Anti-CCP) levels, reactants of acute phase and biochemical markers of oxidative stress before and after 20 days of treatment. MTX+ozone reduced the activity of the disease while MTX merely showed a tendency to decrease the variables. Reactants of acute phase displayed a similar picture. MTX+ozone reduced Anti-CCP levels as well as increased antioxidant system, and decreased oxidative damage whereas MTX did not change. Glutathione correlated with all clinical variables just after MTX+ozone. MTX+ozone increased the MTX clinical response in patients with rheumatoid arthritis. No side effects were observed. These results suggest that ozone can increase the efficacy of MTX probably because both share common therapeutic targets. Medical ozone treatment is capable of being a complementary therapy in the treatment of rheumatoid arthritis. Copyright © 2016 Elsevier B.V. All rights reserved.

ENSO effects on stratospheric ozone: A nudged model perspective

NASA Astrophysics Data System (ADS)

Braesicke, Peter; Kirner, Oliver; Versick, Stefan; Joeckel, Patrick

2015-04-01

The El Niño/Southern Oscillation (ENSO) phenomenon is an important pacemaker for interannual variability in the Earth's atmosphere. ENSO impacts on ozone have been observed and modelled for the stratosphere and the troposphere. It is well recognized that attribution of ENSO variability is important for trend detection. ENSO impacts in low latitudes are easier to detect, because the response emerges close (temporally and spatially) to the forcing. Moving from low to high latitudes it becomes increasingly difficult to isolate ENSO driven variability, due to time-lags involved and many other modes of variability playing a role as well. Here, we use a nudged version of the EMAC chemistry-climate model to evaluate ENSO impacts on ozone over the last 35 years. In the nudged mode configuration EMAC is not entirely free running. The tropospheric meteorology is constrained using ERA-Interim data. Only the upper stratosphere and the composition (including ozone) are calculated without additional observational constraints. Using lagged correlations and supported by additional idealised modelling, we describe the ENSO impact on tropospheric and stratospheric ozone in the EMAC system. We trace the ENSO signal from the tropical lower troposphere to the polar lower and middle stratosphere. Instead of distinguishing tropospheric and stratospheric responses, we present a coherent approach detecting the ENSO signal as a function of altitude, latitude and time, and demonstrate how a concise characterisation of the ENSO impact aids improved trend detection.

Multivariate Regression Analysis of Winter Ozone Events in the Uinta Basin of Eastern Utah, USA

NASA Astrophysics Data System (ADS)

Mansfield, M. L.

2012-12-01

I report on a regression analysis of a number of variables that are involved in the formation of winter ozone in the Uinta Basin of Eastern Utah. One goal of the analysis is to develop a mathematical model capable of predicting the daily maximum ozone concentration from values of a number of independent variables. The dependent variable is the daily maximum ozone concentration at a particular site in the basin. Independent variables are (1) daily lapse rate, (2) daily "basin temperature" (defined below), (3) snow cover, (4) midday solar zenith angle, (5) monthly oil production, (6) monthly gas production, and (7) the number of days since the beginning of a multi-day inversion event. Daily maximum temperature and daily snow cover data are available at ten or fifteen different sites throughout the basin. The daily lapse rate is defined operationally as the slope of the linear least-squares fit to the temperature-altitude plot, and the "basin temperature" is defined as the value assumed by the same least-squares line at an altitude of 1400 m. A multi-day inversion event is defined as a set of consecutive days for which the lapse rate remains positive. The standard deviation in the accuracy of the model is about 10 ppb. The model has been combined with historical climate and oil & gas production data to estimate historical ozone levels.

Climate sensitivity to the lower stratospheric ozone variations

NASA Astrophysics Data System (ADS)

Kilifarska, N. A.

2012-12-01

The strong sensitivity of the Earth's radiation balance to variations in the lower stratospheric ozone—reported previously—is analysed here by the use of non-linear statistical methods. Our non-linear model of the land air temperature (T)—driven by the measured Arosa total ozone (TOZ)—explains 75% of total variability of Earth's T variations during the period 1926-2011. We have analysed also the factors which could influence the TOZ variability and found that the strongest impact belongs to the multi-decadal variations of galactic cosmic rays. Constructing a statistical model of the ozone variability, we have been able to predict the tendency in the land air T evolution till the end of the current decade. Results show that Earth is facing a weak cooling of the surface T by 0.05-0.25 K (depending on the ozone model) until the end of the current solar cycle. A new mechanism for O3 influence on climate is proposed.

Effects of Botrytis and ozone on bracts and flowers of poinsettia cultivars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manning, W.J.; Feder, W.A.; Perkins, I.

1972-09-01

Variability, ranging from complete resistance to extensive susceptibility, was observed when flowers and bracts of 14 cultivars of poinsettia were inoculated with spores of Botrytis cinerea. Flowers and bracts were not visibly injured by exposure to ozone levels up to 45 pphm. Ozone did not have significant fungicidal effects, as measured by visual disease incidence following incubation, when inoculated flowers and bracts were exposed to ozone at 15, 25, 35, and 45 pphm ozone for 4 hr prior to incubation. 8 references, 1 table.

Variability in Tropospheric Ozone over China Derived from Assimilated GOME-2 Ozone Profiles

NASA Astrophysics Data System (ADS)

van Peet, J. C. A.; van der A, R. J.; Kelder, H. M.

2016-08-01

A tropospheric ozone dataset is derived from assimilated GOME-2 ozone profiles for 2008. Ozone profiles are retrieved with the OPERA algorithm, using the optimal estimation method. The retrievals are done on a spatial resolution of 160×160 km on 16 layers ranging from the surface up to 0.01 hPa. By using the averaging kernels in the data assimilation, the algorithm maintains the high resolution vertical structures of the model, while being constrained by observations with a lower vertical resolution.

Modeling forest ecosystem responses to elevated carbon dioxide and ozone using artificial neural networks.

PubMed

Larsen, Peter E; Cseke, Leland J; Miller, R Michael; Collart, Frank R

2014-10-21

Rising atmospheric levels of carbon dioxide and ozone will impact productivity and carbon sequestration in forest ecosystems. The scale of this process and the potential economic consequences provide an incentive for the development of models to predict the types and rates of ecosystem responses and feedbacks that result from and influence of climate change. In this paper, we use phenotypic and molecular data derived from the Aspen Free Air CO2 Enrichment site (Aspen-FACE) to evaluate modeling approaches for ecosystem responses to changing conditions. At FACE, it was observed that different aspen clones exhibit clone-specific responses to elevated atmospheric levels of carbon dioxide and ozone. To identify the molecular basis for these observations, we used artificial neural networks (ANN) to examine above and below-ground community phenotype responses to elevated carbon dioxide, elevated ozone and gene expression profiles. The aspen community models generated using this approach identified specific genes and subnetworks of genes associated with variable sensitivities for aspen clones. The ANN model also predicts specific co-regulated gene clusters associated with differential sensitivity to elevated carbon dioxide and ozone in aspen species. The results suggest ANN is an effective approach to predict relevant gene expression changes resulting from environmental perturbation and provides useful information for the rational design of future biological experiments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ozone Depletion at Mid-Latitudes: Coupling of Volcanic Aerosols and Temperature Variability to Anthropogenic Chlorine

NASA Technical Reports Server (NTRS)

Solomon, S.; Portmann, R. W.; Garcia, R. R.; Randel, W.; Wu, F.; Nagatani, R.; Gleason, J.; Thomason, L.; Poole, L. R.; McCormick, M. P.

1998-01-01

Satellite observations of total ozone at 40-60 deg N are presented from a variety of instruments over the time period 1979-1997. These reveal record low values in 1992-3 (after Pinatubo) followed by partial but incomplete recovery. The largest post-Pinatubo reductions and longer-term trends occur in spring, providing a critical test for chemical theories of ozone depletion. The observations are shown to be consistent with current understanding of the chemistry of ozone depletion when changes in reactive chlorine and stratospheric aerosol abundances are considered along with estimates of wave-driven fluctuations in stratospheric temperatures derived from global temperature analyses. Temperature fluctuations are shown to make significant contributions to model calculated northern mid-latitude ozone depletion due to heterogeneous chlorine activation on liquid sulfate aerosols at temperatures near 200-210 K (depending upon water vapor pressure), particularly after major volcanic eruptions. Future mid-latitude ozone recovery will hence depend not only on chlorine recovery but also on temperature trends and/or variability, volcanic activity, and any trends in stratospheric sulfate aerosol.

Spectral analyses, climatology, and interannual variability of Nimbus-7 TOMS version 6 total column ozone

NASA Technical Reports Server (NTRS)

Stanford, J. L.; Ziemke, J. R.; Mcpeters, R. D.; Krueger, A. J.; Bhartia, P. K.

1995-01-01

This reference publication presents selected results from space-time spectral analyses of 13 years of version 6 daily global ozone fields from the Total Ozone Mapping Spectrometer (TOMS). One purpose is to illustrate more quantitatively the well-known richness of structure and variation in total ozone. A second purpose is to provide, for use by modelers and for comparison with other analysts' work, quantitative measures of zonal waves 1, 2, 3, and medium-scale waves 4-7 in total ozone. Their variations throughout the year and at a variety of latitudes are presented, from equatorial to polar regions. The 13-year averages are given, along with selected individual years which illustrate year-to-year variability. The largest long wave amplitudes occur in the polar winters and early springs of each hemisphere, and are related to strong wave amplification during major warning events. In low attitudes total ozone wave amplitudes are an order of magnitude smaller than at high latitudes. However, TOMS fields contain a number of equatorial dynamical features, including Rossby-gravity and Kelvin waves.

Space observations of aerosols and ozone; Proceedings of the Topical Meeting, Ottawa, Canada, May 16-June 2, 1982

NASA Technical Reports Server (NTRS)

Mccormick, M. P. (Editor); Lovill, J. E.

1982-01-01

The measurement of aerosols from space is discussed, taking into account the role of aerosols in climate, instrumentation and further measurement systems, retrieval procedures, measurements and observations, ground truth measurements, and effects on remote sensing and on climate. Aspects of ozone variability in the middle atmosphere are explored, giving attention to the quasi-biennial oscillation in equatorial stratospheric temperatures and total ozone, global pictures on the ozone field from high altitudes from DE-1, measurements of atmospheric ozone from aircraft and from balloons, a mesospheric ozone profile at sunset, periodic and aperiodic ozone variations in the middle and upper stratosphere, solar eclipse induced variations in mesospheric ozone concentrations, and solar UV and ozone balloon measurements. The determination of aerosol optical depth is considered along with a method for estimating cross radiance.

Artificial neural network model for ozone concentration estimation and Monte Carlo analysis

NASA Astrophysics Data System (ADS)

Gao, Meng; Yin, Liting; Ning, Jicai

2018-07-01

Air pollution in urban atmosphere directly affects public-health; therefore, it is very essential to predict air pollutant concentrations. Air quality is a complex function of emissions, meteorology and topography, and artificial neural networks (ANNs) provide a sound framework for relating these variables. In this study, we investigated the feasibility of using ANN model with meteorological parameters as input variables to predict ozone concentration in the urban area of Jinan, a metropolis in Northern China. We firstly found that the architecture of network of neurons had little effect on the predicting capability of ANN model. A parsimonious ANN model with 6 routinely monitored meteorological parameters and one temporal covariate (the category of day, i.e. working day, legal holiday and regular weekend) as input variables was identified, where the 7 input variables were selected following the forward selection procedure. Compared with the benchmarking ANN model with 9 meteorological and photochemical parameters as input variables, the predicting capability of the parsimonious ANN model was acceptable. Its predicting capability was also verified in term of warming success ratio during the pollution episodes. Finally, uncertainty and sensitivity analysis were also performed based on Monte Carlo simulations (MCS). It was concluded that the ANN could properly predict the ambient ozone level. Maximum temperature, atmospheric pressure, sunshine duration and maximum wind speed were identified as the predominate input variables significantly influencing the prediction of ambient ozone concentrations.

North Atlantic Oscillation and pollutants variability in Europe: model analysis and measurements intercomparison

NASA Astrophysics Data System (ADS)

Pausata, F.; Pozzoli, L.; Van Dingenen, R.; Vignati, E.; Cavalli, F.; Dentener, F. J.

2013-12-01

Ozone pollution and particulate matter (PM) represent a serious health and environmental problem. While ozone pollution is mostly produced by photochemistry in summer, PM is of main concern during winter. Both pollutants can be influenced nt only by local scale processes but also by long range transport driven by the atmospheric circulation and stratospheric ozone intrusions. We analyze the role of large scale atmospheric circulation variability in the North Atlantic basin in determining surface ozone and PM concentrations over Europe. Here, we show, using ground station measurements and a coupled atmosphere-chemistry model simulation for the period 1980-2005, that with regard to ozone the North Atlantic Oscillation (NAO) does affect surface ozone concentrations - on a monthly timescale, over 10 ppbv in southwestern, central and northern Europe - during all seasons except fall. We find that the first Principal Component, computed from the time variation of the sea level pressure (SLP) field, detects the atmosphere circulation/ozone relationship not only in winter and spring but also during summer, when the atmospheric circulation weakens and regional photochemical processes peak. Given the NAO forecasting skill at intraseasonal time scale, the first Principal Component of the SLP field could be used as an indicator to identify areas more exposed to forthcoming ozone pollution events. Finally, our results suggest that the increasing baseline ozone in western and northern Europe during the 1990s could be related to the prevailing positive phase of the NAO in that period. With regard to PM, our study shows that in winter the NAO modulates surface PM concentrations accounting in average up to 30% of the total PM variability. During positive NAO phases, positive PM anomalies occur over southern Europe, and negative anomalies in central-northern Europe. A positve shift of the NAO mean states, hence, leads to an increase in cardiac and resipratory morbidity related to PM exposure in the Mediterranean countries with up to over 5000 more deaths per 20 million people for a 2000 emission inventory.

Vertical distribution and sources of tropospheric ozone over South China in spring 2004: Ozonesonde measurements and modeling analysis

NASA Astrophysics Data System (ADS)

Zhang, Y.; Liu, H.; Crawford, J. H.; Considine, D. B.; Chan, C.; Scientific Team Of Tapto

2010-12-01

The Transport of Air Pollutant and Tropospheric Ozone over China (TAPTO-China) science initiative is a two-year (TAPTO 2004 and 2005) field measurement campaign to help improve our understanding of the physical and chemical processes that control the tropospheric ozone budget over the Chinese subcontinent (including the Asian Pacific rim) and its surrounding SE Asia. In this paper, we use two state-of-the-art 3-D global chemical transport models (GEOS-Chem and Global Modeling Initiative or GMI) to examine the characteristics of vertical distribution and quantify the sources of tropospheric ozone by analysis of TAPTO in-situ ozonesonde data obtained at five stations in South China during spring (April and May) 2004: Lin’an (30.30N, 119.75E), Tengchong (25.01N, 98.30E), Taipei (25.0N, 121.3E), Hong Kong (22.21N, 114.30E) and Sanya (18.21N, 110.31E). The observed tropospheric ozone concentrations show strong spatial and temporal variability, which is largely captured by the models. The models simulate well the observed vertical gradients of tropospheric ozone at higher latitudes but are too low at lower latitudes. Model tagged ozone simulations suggest that stratosphere has a large impact on the upper and middle troposphere (UT/MT) at Lin’an and Tengchong. Continental SE Asian biomass burning emissions are maximum in March but still contribute significantly to the photochemical production of tropopheric ozone in South China in early April. Asian anthropogenic emissions are the major contribution to lower tropospheric ozone at all stations. On the other hand, there are episodes of influence from European/North American anthropogenic emissions. For example, model tagged ozone simulations show that over Lin’an in April 2004, stratosphere contributes 20% (13 ppbv) at 5 km, Asian boundary layer contributes 70% (46 ppbv) to ozone in the boundary layer, European boundary layer contributes 5% (3-4 ppbv) at 1.2 km, and North American boundary layer contributes 4.5% (3 ppbv) at 1.2 km. Lastly, our analysis suggests that lightning NOx emissions have substantial impact on the UT/MT ozone over South China. We argue that model underestimate of ozone concentrations, especially at lower latitudes, is likely due to too low lightning NOx emissions.

Elevated ozone affects C, N and P ecological stoichiometry and nutrient resorption of two poplar clones.

PubMed

Shang, Bo; Feng, Zhaozhong; Li, Pin; Calatayud, Vicent

2018-03-01

The effects of elevated ozone on C (carbon), N (nitrogen) and P (phosphorus) ecological stoichiometry and nutrient resorption in different organs including leaves, stems and roots were investigated in poplar clones 546 (P. deltoides cv. '55/56' × P. deltoides cv. 'Imperial') and 107 (P. euramericana cv. '74/76') with a different sensitivity to ozone. Plants were exposed to two ozone treatments, NF (non-filtered ambient air) and NF60 (NF with targeted ozone addition of 60 ppb), for 96 days in open top chambers (OTCs). Significant ozone effects on most variables of C, N and P ecological stoichiometry were found except for the C concentration and the N/P in different organs. Elevated ozone increased both N and P concentrations of individual organs while for C/N and C/P ratios a reduction was observed. On these variables, ozone had a greater effect for clone 546 than for clone 107. N concentrations of different leaf positions ranked in the order upper > middle > lower, showing that N was transferred from the lower senescent leaves to the upper ones. This was also indicative of N resorption processes, which increased under elevated ozone. N resorption of clone 546 was 4 times larger than that of clone 107 under ambient air (NF). However, elevated ozone (NF60) had no significant effect on P resorption for both poplar clones, suggesting that their growth was only limited by N, while available P in the soil was enough to sustain growth. Understanding ecological stoichiometric responses under ozone stress is crucial to predict future effects on ecological processes and biogeochemical cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stratospheric Ozone Intercomparison Campaign (STOIC) 1989: Overview

NASA Technical Reports Server (NTRS)

Margitan, J. J.; Barnes, R. A.; Brothers, G. B.; Butler, J.; Burris, J.; Connor, B. J.; Ferrare, R. A.; Kerr, J. B.; Komhyr, W. D.; McCormick, M. P.;

Antarctic Climate Variability: Covariance of Ozone and Sea Ice in Atmosphere - Ocean Coupled Model Simulations

NASA Astrophysics Data System (ADS)

Jrrar, Amna; Abraham, N. Luke; Pyle, John A.; Holland, David

2014-05-01

Changes in sea ice significantly modulate climate change because of its high reflective and insulating nature. While Arctic Sea Ice Extent (SIE) shows a negative trend. Antarctic SIE shows a weak but positive trend, estimated at 0.127 x 106 km2 per decade. The trend results from large regional cancellations, more ice in the Weddell and the Ross seas, and less ice in the Amundsen - Bellingshausen seas. A number of studies had demonstrated that stratospheric ozone depletion has had a major impact on the atmospheric circulation, causing a positive trend in the Southern Annular Mode (SAM), which has been linked to the observed positive trend in autumn sea ice in the Ross Sea. However, other modelling studies show that models forced with prescribed ozone hole simulate decreased sea ice in all regions comparative to a control run. A recent study has also shown that stratospheric ozone recovery will mitigate Antarctic sea ice loss. To verify this assumed relationship, it is important first to investigate the covariance between ozone's natural (dynamical) variability and Antarctic sea ice distribution in pre-industrial climate, to estimate the trend due to natural variability. We investigate the relationship between anomalous Antarctic ozone years and the subsequent changes in Antarctic sea ice distribution in a multidecadal control simulation using the AO-UMUKCA model. The model has a horizontal resolution of 3.75 X 2.5 degrees in longitude and latitude; and 60 hybrid height levels in the vertical, from the surface up to a height of 84 km. The ocean component is the NEMO ocean model on the ORCA2 tripolar grid, and the sea ice model is CICE. We evaluate the model's performance in terms of sea ice distribution, and we calculate sea ice extent trends for composites of anomalously low versus anomalously high SH polar ozone column. We apply EOF analysis to the seasonal anomalies of sea ice concentration, MSLP, and Z 500, and identify the leading climate modes controlling the variability of Antarctic sea ice in each case, and study their relationship with SH polar ozone column.

Modeling mechanisms of susceptibility in vitro: Differential activation of the MAP kinase ERK, but not p38, mediates variability and adaptation in the pro-inflammatory response to ozone

EPA Science Inventory

Ozone is a ubiquitous ambient air pollutant that causes pulmonary inflammation upon exposure. The ozone-induced inflammatory response varies by orders of magnitude and the range of variation in “healthy” individuals extends beyond that of “susceptible” po...

Global QBO in circulation and ozone. Part 1: Reexamination of observational evidence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tung, K.K.; Yang, H.

1994-10-01

Observational evidence for a global quasi-biennial oscillation (QBO) pattern is reviewed. In particular, the presence of an extratropical, as well as an equatorial, component of the QBO signal in column ozone is established. It is found that the ozone interannual variability is such that as one moves away from the Tropics, the frequency spectrum of the anomaly changes from one that is dominated by the equatorial QBO frequency of 1/30 mo to a two-peak spectrum around the two frequencies: 1/30 mo and 1/20 mo. Instead of treating the 1/20 mo frequency as a separate phenomenon to be filtered away inmore » extracting the QBO in the extratropics, as was previously done, the authors argue that both peaks are integral parts of the extratropical QBO phenomenon. The 1/20 mo frequency happens to be the difference combination of the QBO frequency 1/30 mo and the annual frequency 1/12 mo. Therefore, it can represent the result of the QBO modulating an annual cycle. The authors suggest that previous methods of extracting the extratropical QBO signal severely underestimated the contribution of the QBO to the interannual variability of ozone when data are filtered to pass only the component with the period of equatorial QBO. Further, it is argued that the transport of equatorial QBO ozone anomaly by a non-QBO circulation can at most account for 6-8 Dobson units (DU) of the observed interannual variability of column ozone in the extratropics. The remaining variability (up to 20 DU) probably cannot be produced without an anomaly in the transporting circulation in the extratropics.« less

Total ozone derived from UV spectrophotometer measurements on the NASA CV-990 aircraft for the fall 1976 latitude survey flights

NASA Technical Reports Server (NTRS)

Hanser, F. A.

1977-01-01

An ultraviolet interference filter spectrophotometer was modified to use a photodiode and was flown on latitude survey flights in the fall of 1976. Comparison with Dobson station total ozone values shows agreement between UVS and Dobson total ozone of + or - 2 percent. The procedure used to convert UVS measured ozone above the aircraft altitude to total ozone above ground level introduces an additional 2 percent deviation for very high altitude UVS ozone data. Under stable aircraft operating conditions, the UVS derived ozone values have a variability, or reproducibility, of better than + or -1 percent. The UVS data from the latitude survey flights yield a detailed latitude profile of total ozone over the Pacific Ocean during November 1976. Significant latitudinal structure in total ozone is found at the middle latitudes (30 deg to 40 deg N and S).

Long-term meteorologically independent trend analysis of ozone air quality at an urban site in the greater Houston area.

PubMed

Botlaguduru, Venkata S V; Kommalapati, Raghava R; Huque, Ziaul

2018-04-19

The Houston-Galveston-Brazoria (HGB) area of Texas has a history of ozone exceedances and is currently classified under moderate nonattainment status for the 2008 8-hr ozone standard of 75 ppb. The HGB area is characterized by intense solar radiation, high temperature, and humidity, which influence day-to-day variations in ozone concentrations. Long-term air quality trends independent of meteorological influence need to be constructed for ascertaining the effectiveness of air quality management in this area. The Kolmogorov-Zurbenko (KZ) filter technique used to separate different scales of motion in a time series, is applied in the current study for maximum daily 8-hr (MDA8) ozone concentrations at an urban site (EPA AQS Site ID: 48-201-0024, Aldine) in the HGB area. This site located within 10 miles of downtown Houston and the George Bush Intercontinental Airport, was selected for developing long-term meteorologically independent MDA8 ozone trends for the years 1990-2016. Results from this study indicate a consistent decrease in meteorologically independent MDA8 ozone between 2000-2016. This pattern could be partially attributed to a reduction in underlying NO X emissions, particularly that of lowering nitrogen dioxide (NO 2 ) levels, and a decrease in the release of highly reactive volatile organic compounds (HRVOC). Results also suggest solar radiation to be most strongly correlated to ozone, with temperature being the secondary meteorological control variable. Relative humidity and wind speed have tertiary influence at this site. This study observed that meteorological variability accounts for a high of 61% variability in baseline ozone (low-frequency component, sum of long-term and seasonal components), while 64% of the change in long-term MDA8 ozone post-2000 could be attributed to NO X emissions reduction. Long-term MDA8 ozone trend component was estimated to be decreasing at a linear rate of 0.412 ± 0.007 ppb/yr for the years 2000-2016, and 0.155 ± 0.005 ppb/yr for the overall period of 1990-2016. Implications Statement The effectiveness of air emission controls can be evaluated by developing long-term air quality trends independent of meteorological influences. KZ filter technique is a well-established method to separate an air quality time-series into: short-term, seasonal and long-term components. This paper applies the KZ filter technique to MDA8 ozone data between 1990-2016 at an urban site in the Greater Houston area and estimates the variance accounted for, by the primary meteorological control variables. Estimates for linear trends of MDA8 ozone are calculated and underlying causes are investigated to provide a guidance for further investigation into air quality management of the Greater Houston Area.

The influence of changing UVB radiation in near-surface ozone time series

NASA Astrophysics Data System (ADS)

BröNnimann, Stefan; Voigt, Stefan; Wanner, Heinz

2000-04-01

UVB radiation plays an important role in tropospheric photochemistry since it determines the rate of ozone photolysis J(O1D) and subsequent formation of OH radicals. Consequently, changes of UVB radiation, for example due to changes of the stratospheric ozone amount, could alter the concentration of reactive tropospheric gases including ozone. An observation-based attempt is made to quantify the effect of changing UVB radiation on surface ozone peaks on a day-to-day scale using a time series of measurements at a Swiss mountain site. Seven years data of ozone, NO, NOx, and meteorological measurements from Chaumont (1140 m above sea level (asl)), total ozone and UVB measurements from Arosa (1847 m asl), and surface albedo from satellite observations are investigated. The study is restricted to fair weather days with moderately high NOx concentrations. Multiple regression analysis is performed using chemical, meteorological, and UV dependent variables to predict afternoon ozone peaks. From autumn to spring, positive deviations of ozone peaks are clearly connected with positive UVB deviations. The relation is statistically significant only in part of the seasonal data subsets; however, it is consistent with model studies. The estimated net effect on ozone peaks is normally within a range of 4 ppb, a range of about 6 ppb is predicted for large UVB changes. Applying the coefficients for the large interannual variability of the stratospheric ozone layer observed in spring in the last 10 years results in a range of variation of at most 1 to 1.5 ppb for monthly mean ozone peaks. For trends of J(O1D) from 1970 to 1990, a trend bias of surface ozone peaks on polluted fair weather days of less than 0.12 ppb/yr is calculated. Although the numbers are rather small, they may play a role in certain circumstances.

Ground-based assessment of the bias and long-term stability of fourteen limb and occultation ozone profile data records.

PubMed

Hubert, D; Lambert, J-C; Verhoelst, T; Granville, J; Keppens, A; Baray, J-L; Cortesi, U; Degenstein, D A; Froidevaux, L; Godin-Beekmann, S; Hoppel, K W; Kyrölä, E; Leblanc, T; Lichtenberg, G; McElroy, C T; Murtagh, D; Nakane, H; Querel, R; Russell, J M; Salvador, J; Smit, H G J; Stebel, K; Steinbrecht, W; Strawbridge, K B; Stübi, R; Swart, D P J; Taha, G; Thompson, A M; Urban, J; van Gijsel, J A E; von der Gathen, P; Walker, K A; Wolfram, E; Zawodny, J M

2016-01-01

The ozone profile records of a large number of limb and occultation satellite instruments are widely used to address several key questions in ozone research. Further progress in some domains depends on a more detailed understanding of these data sets, especially of their long-term stability and their mutual consistency. To this end, we made a systematic assessment of fourteen limb and occultation sounders that, together, provide more than three decades of global ozone profile measurements. In particular, we considered the latest operational Level-2 records by SAGE II, SAGE III, HALOE, UARS MLS, Aura MLS, POAM II, POAM III, OSIRIS, SMR, GOMOS, MIPAS, SCIAMACHY, ACE-FTS and MAESTRO. Central to our work is a consistent and robust analysis of the comparisons against the ground-based ozonesonde and stratospheric ozone lidar networks. It allowed us to investigate, from the troposphere up to the stratopause, the following main aspects of satellite data quality: long-term stability, overall bias, and short-term variability, together with their dependence on geophysical parameters and profile representation. In addition, it permitted us to quantify the overall consistency between the ozone profilers. Generally, we found that between 20-40 km the satellite ozone measurement biases are smaller than ±5 %, the short-term variabilities are less than 5-12% and the drifts are at most ±5% decade -1 (or even ±3 % decade -1 for a few records). The agreement with ground-based data degrades somewhat towards the stratopause and especially towards the tropopause where natural variability and low ozone abundances impede a more precise analysis. In part of the stratosphere a few records deviate from the preceding general conclusions; we identified biases of 10% and more (POAM II and SCIAMACHY), markedly higher single-profile variability (SMR and SCIAMACHY), and significant long-term drifts (SCIAMACHY, OSIRIS, HALOE, and possibly GOMOS and SMR as well). Furthermore, we reflected on the repercussions of our findings for the construction, analysis and interpretation of merged data records. Most notably, the discrepancies between several recent ozone profile trend assessments can be mostly explained by instrumental drift. This clearly demonstrates the need for systematic comprehensive multi-instrument comparison analyses.

Ground-Based Assessment of the Bias and Long-Term Stability of Fourteen Limb and Occultation Ozone Profile Data Records

NASA Technical Reports Server (NTRS)

Hubert, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; Keppens, A.; Baray, J.-L.; Cortesi, U.; Degenstein, D. A.; Froidevaux, L.; Godin-Beekmann, S.;

Ground-based assessment of the bias and long-term stability of fourteen limb and occultation ozone profile data records

PubMed Central

Hubert, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; Keppens, A.; Baray, J.-L.; Cortesi, U.; Degenstein, D. A.; Froidevaux, L.; Godin-Beekmann, S.; Hoppel, K. W.; Kyrölä, E.; Leblanc, T.; Lichtenberg, G.; McElroy, C. T.; Murtagh, D.; Nakane, H.; Querel, R.; Russell, J. M.; Salvador, J.; Smit, H. G. J.; Stebel, K.; Steinbrecht, W.; Strawbridge, K. B.; Stübi, R.; Swart, D. P. J.; Taha, G.; Thompson, A. M.; Urban, J.; van Gijsel, J. A. E.; von der Gathen, P.; Walker, K. A.; Wolfram, E.; Zawodny, J. M.

2018-01-01

The ozone profile records of a large number of limb and occultation satellite instruments are widely used to address several key questions in ozone research. Further progress in some domains depends on a more detailed understanding of these data sets, especially of their long-term stability and their mutual consistency. To this end, we made a systematic assessment of fourteen limb and occultation sounders that, together, provide more than three decades of global ozone profile measurements. In particular, we considered the latest operational Level-2 records by SAGE II, SAGE III, HALOE, UARS MLS, Aura MLS, POAM II, POAM III, OSIRIS, SMR, GOMOS, MIPAS, SCIAMACHY, ACE-FTS and MAESTRO. Central to our work is a consistent and robust analysis of the comparisons against the ground-based ozonesonde and stratospheric ozone lidar networks. It allowed us to investigate, from the troposphere up to the stratopause, the following main aspects of satellite data quality: long-term stability, overall bias, and short-term variability, together with their dependence on geophysical parameters and profile representation. In addition, it permitted us to quantify the overall consistency between the ozone profilers. Generally, we found that between 20–40 km the satellite ozone measurement biases are smaller than ±5 %, the short-term variabilities are less than 5–12% and the drifts are at most ±5% decade−1 (or even ±3 % decade−1 for a few records). The agreement with ground-based data degrades somewhat towards the stratopause and especially towards the tropopause where natural variability and low ozone abundances impede a more precise analysis. In part of the stratosphere a few records deviate from the preceding general conclusions; we identified biases of 10% and more (POAM II and SCIAMACHY), markedly higher single-profile variability (SMR and SCIAMACHY), and significant long-term drifts (SCIAMACHY, OSIRIS, HALOE, and possibly GOMOS and SMR as well). Furthermore, we reflected on the repercussions of our findings for the construction, analysis and interpretation of merged data records. Most notably, the discrepancies between several recent ozone profile trend assessments can be mostly explained by instrumental drift. This clearly demonstrates the need for systematic comprehensive multi-instrument comparison analyses. PMID:29743958

TRPA1 mediates changes in heart rate variability and cardiac ...

EPA Pesticide Factsheets

Short-term exposure to ambient air pollution is linked with adverse cardiovascular effects. While previous research focused primarily on particulate matter-induced responses, gaseous air pollutants also contribute to cause short-term cardiovascular effects. Mechanisms underlying such effects have not been adequately described; however, the immediate nature of the response suggests involvement of irritant neural activation and downstream autonomic dysfunction. Thus, this study examines the role of TRPA1, an irritant sensory receptor found in the airways, in the cardiac response of mice to acrolein and ozone. Conscious unrestrained wild-type C57BL/6 (WT) and TRPA1 knockout (KO) mice implanted with radiotelemeters were exposed once to 3ppm acrolein, 0.3ppm ozone, or filtered air. Heart rate (HR) and electrocardiogram (ECG) were recorded continuously before, during and after exposure. Analysis of ECG morphology, incidence of arrhythmia and heart rate variability (HRV) were performed. Cardiac mechanical function was assessed using a Langendorff perfusion preparation 24h post-exposure. Acrolein exposure increased HRV independent of HR, as well as incidence of arrhythmia. Acrolein also increased left ventricular developed pressure in WT mice at 24h post-exposure. Ozone did not produce any changes in cardiac function. Neither gas produced ECG effects, changes in HRV, arrhythmogenesis, or mechanical function in KO mice. These data demonstrate that a single exposure to ac

A mid-latitude ozone model for the US standard atmosphere, 1975 (summary)

NASA Technical Reports Server (NTRS)

Krueger, A. J.; Minzner, R. A.

1974-01-01

A mid-latitude, Northern-Hemisphere model of the daytime ozone distribution in the troposphere, stratosphere, and lower mesosphere was constructed. Data from rocket soundings in the latitude range 45 deg N + or - 15 deg, results of balloon soundings at altitudes from 41 to 47 deg N, and latitude gradients from satellite ozone observations were combined to produce estimates of the annual mean ozone concentration and its variability at heights to 72 km for an effective latitude of 45 deg N. The model is a revision, for heights above 26 km, of the tentative Mid-Latitude Ozone Model.

Total ozone and surface temperature correlations during 1972 - 1981

NASA Technical Reports Server (NTRS)

Parsons, C. L.

1983-01-01

Ten years of Dobson spectrophotometer total ozone measurements and surface temperature observations were used to construct monthly mean values of the two parameters. The variability of both parameters is greatest in the months of January and February. Indeed, in January there is an apparent correlation between high total ozone values and abnormally low surface temperatures. However, the correlation does not hold in February. By reviewing the history of stratospheric warmings during this period, it is argued that the ozone and surface temperature correlation is influenced by the advection or lack of advection of ozone rich arctic air resulting from sudden stratospheric warmings.

Ozone time scale decomposition and trend assessment from surface observations

NASA Astrophysics Data System (ADS)

Boleti, Eirini; Hueglin, Christoph; Takahama, Satoshi

2017-04-01

Emissions of ozone precursors have been regulated in Europe since around 1990 with control measures primarily targeting to industries and traffic. In order to understand how these measures have affected air quality, it is now important to investigate concentrations of tropospheric ozone in different types of environments, based on their NOx burden, and in different geographic regions. In this study, we analyze high quality data sets for Switzerland (NABEL network) and whole Europe (AirBase) for the last 25 years to calculate long-term trends of ozone concentrations. A sophisticated time scale decomposition method, called the Ensemble Empirical Mode Decomposition (EEMD) (Huang,1998;Wu,2009), is used for decomposition of the different time scales of the variation of ozone, namely the long-term trend, seasonal and short-term variability. This allows subtraction of the seasonal pattern of ozone from the observations and estimation of long-term changes of ozone concentrations with lower uncertainty ranges compared to typical methodologies used. We observe that, despite the implementation of regulations, for most of the measurement sites ozone daily mean values have been increasing until around mid-2000s. Afterwards, we observe a decline or a leveling off in the concentrations; certainly a late effect of limitations in ozone precursor emissions. On the other hand, the peak ozone concentrations have been decreasing for almost all regions. The evolution in the trend exhibits some differences between the different types of measurement. In addition, ozone is known to be strongly affected by meteorology. In the applied approach, some of the meteorological effects are already captured by the seasonal signal and already removed in the de-seasonalized ozone time series. For adjustment of the influence of meteorology on the higher frequency ozone variation, a statistical approach based on Generalized Additive Models (GAM) (Hastie,1990;Wood,2006), which corrects for meteorological effects, has been developed in order to a) investigate if trends are masked by meteorological variability and b) to understand which part of the observed trends is meteorology driven. By correlating short-term variation of ozone, as obtained from the EEMD, with the corresponding short-term variation of relevant meteorological parameters, we subtract the variation of ozone concentrations that is related to the meteorological effects explained by the GAM. We find that higher frequency meteorological correction reduces further the uncertainty in trend estimation by a small factor. In addition, the seasonal variability of ozone as obtained from the EEMD has been studied in more detail for possible changes in its behavior. A shortening of the seasonal cycle was observed, i.e. reduction of maximum and in-crease of minimum concentration per year, while the occurrence of maximum is shifted to earlier times during a year. In summary, we present a sophisticated and consistent approach for detecting and categorizing trends and meteorological influences on ozone concentrations in long-term measurements across Europe.

THE 1974 OZONE EPISODE IN THE BALTIMORE-TO-RICHMOND CORRIDOR

EPA Science Inventory

An ozone alert in July of 1974 in the Washington, D.C., area is examined in detail. Ozone data for 16 stations in the Richmond-to-Baltimore corridor are examined in conjunction with meteorological data for the alert period. Emphases are given to trajectories of the air between th...

Comparison of HIPWAC and Mars Express SPICAM Observations of Ozone on Mars 2006-2008 and Variation from 1993 IRHS Observations

NASA Technical Reports Server (NTRS)

Fast, Kelly E.; Kostiuk, Theodor; Lefevre, Frank; Hewagama, Tilak; Livengood, Timothy A.; Delgado, Juan D.; Annen, John; Sonnabend, Guido

2009-01-01

Ozone is a tracer of photochemistry in the atmosphere of Mars and an observable used to test predictions of photochemical models. We present a comparison of retrieved ozone abundances on Mars using ground-based infrared heterodyne measurements by NASA Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) and space-based Mars Express Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) ultraviolet measurements. Ozone retrievals from simultaneous measurements in February 2008 were very consistent (0.8 microns-atm), as were measurements made close in time (ranging from less than 1 to greater than 8 microns-atm) during this period and during opportunities in October 2006 and February 2007. The consistency of retrievals from the two different observational techniques supports combining the measurements for testing photochemistry-coupled general circulation models and for investigating variability over the long-term between spacecraft missions. Quantitative comparison with ground-based measurements by NASA'GSFC's Infrared Heterodyne Spectrometer (IRHS) in 1993 reveals 2-4 times more ozone at low latitudes than in 2008 at the same season, and such variability was not evident over the shorter period of the Mars Express mission. This variability may be due to cloud activity.

Does Topical Ozone Therapy Improve Patient Comfort After Surgical Removal of Impacted Mandibular Third Molar? A Randomized Controlled Trial.

PubMed

Sivalingam, Varun P; Panneerselvam, Elavenil; Raja, Krishnakumar V B; Gopi, Gayathri

2017-01-01

To assess the influence of topical ozone administration on patient comfort after third molar surgery. A single-blinded randomized controlled clinical trial was designed involving patients who required removal of bilateral impacted mandibular third molars. The predictor variable was the postoperative medication used after third molar surgery. Using the split-mouth design, the study group received topical ozone without postoperative systemic antibiotics, whereas the control group did not receive ozone but only systemic antibiotics. The 2 groups were prescribed analgesics for 2 days. The assessing surgeon was blinded to treatment assignment. The primary outcome variables were postoperative mouth opening, pain, and swelling. The secondary outcome variable was the number of analgesic doses required by each group on postoperative days 3 to 5. Data analysis involved descriptive statistics, paired t tests, and 2-way analysis of variance with repeated measures (P < .05). SPSS 20.0 was used for data analysis. The study sample included 33 patients (n = 33 in each group). The study group showed statistically relevant decreases in postoperative pain, swelling, and trismus. Further, the number of analgesics required was smaller than in the control group. No adverse effects of ozone gel were observed in any patient. Ozone gel was found to be an effective topical agent that considerably improves patient comfort postoperatively and can be considered a substitute of postoperative systemic antibiotics. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Mid-latitude storm track variability and its influence on atmospheric composition

NASA Astrophysics Data System (ADS)

Knowland, K. E.; Doherty, R. M.; Hodges, K.

2013-12-01

Using the storm tracking algorithm, TRACK (Hodges, 1994, 1995, 1999), we have studied the behaviour of storm tracks in the North Atlantic basin, using 850-hPa relative vorticity from the ERA-Interim Re-analysis (Dee et al., 2011). We have correlated surface ozone measurements at rural coastal sites in Europe to the storm track data to explore the role mid-latitude cyclones and their transport of pollutants play in determining surface air quality in Western Europe. To further investigate this relationship, we have used the Monitoring Atmospheric Composition Climate (MACC) Re-analysis dataset (Inness et al., 2013) in TRACK. The MACC Re-analysis is a 10-year dataset which couples a chemistry transport model (Mozart-3; Stein 2009, 2012) to an extended version of the European Centre for Medium-Range Weather Forecasts' (ECMWF) Integrated Forecast System (IFS). Storm tracks in the MACC Re-analysis compare well to the storm tracks using the ERA-Interim Re-analysis for the same 10-year period, as both are based on ECMWF IFSs. We also compare surface ozone values from MACC to surface ozone measurements previously studied. Using TRACK, we follow ozone (O3) and carbon monoxide (CO) through the life cycle of storms from North America to Western Europe. Along the storm tracks, we examine the distribution of CO and O3 within 6 degrees of the center of each storm and vertically at different pressure levels in the troposphere. We hope to better understand the mechanisms with which pollution is vented from the boundary layer to the free troposphere, as well as transport of pollutants to rural areas. Our hope is to give policy makers more detailed information on how climate variability associated with storm tracks between 1979-2013 may affect air quality in Northeast USA and Western Europe.

Combining multiple regression and principal component analysis for accurate predictions for column ozone in Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Rajab, Jasim M.; MatJafri, M. Z.; Lim, H. S.

2013-06-01

This study encompasses columnar ozone modelling in the peninsular Malaysia. Data of eight atmospheric parameters [air surface temperature (AST), carbon monoxide (CO), methane (CH4), water vapour (H2Ovapour), skin surface temperature (SSKT), atmosphere temperature (AT), relative humidity (RH), and mean surface pressure (MSP)] data set, retrieved from NASA's Atmospheric Infrared Sounder (AIRS), for the entire period (2003-2008) was employed to develop models to predict the value of columnar ozone (O3) in study area. The combined method, which is based on using both multiple regressions combined with principal component analysis (PCA) modelling, was used to predict columnar ozone. This combined approach was utilized to improve the prediction accuracy of columnar ozone. Separate analysis was carried out for north east monsoon (NEM) and south west monsoon (SWM) seasons. The O3 was negatively correlated with CH4, H2Ovapour, RH, and MSP, whereas it was positively correlated with CO, AST, SSKT, and AT during both the NEM and SWM season periods. Multiple regression analysis was used to fit the columnar ozone data using the atmospheric parameter's variables as predictors. A variable selection method based on high loading of varimax rotated principal components was used to acquire subsets of the predictor variables to be comprised in the linear regression model of the atmospheric parameter's variables. It was found that the increase in columnar O3 value is associated with an increase in the values of AST, SSKT, AT, and CO and with a drop in the levels of CH4, H2Ovapour, RH, and MSP. The result of fitting the best models for the columnar O3 value using eight of the independent variables gave about the same values of the R (≈0.93) and R2 (≈0.86) for both the NEM and SWM seasons. The common variables that appeared in both regression equations were SSKT, CH4 and RH, and the principal precursor of the columnar O3 value in both the NEM and SWM seasons was SSKT.

Numerical simulation of ozone loss in the Antarctic winters 2005-2008: Comparison with MLS measurements

NASA Astrophysics Data System (ADS)

Kuttippurath, J.; Godin-Beekmann, S.; Lefevre, F.; Pazmino, A.

2009-04-01

The ozone loss in the recent Antarctic winters were high enough to pause a lag in the recovery phase of stratospheric ozone above this continent. We quantitatively examine the extent of ozone loss variability during 2005-2008 with simulations from a high resolution chemical transport model, MIMOSA-CHIM. The simulated results are cross-checked with the observed loss from Microwave Limb Sounder (MLS) satellite sensor data. This study uses the vortex averaged data at the potential temperature level 475 K from both MIMOSA and MLS to estimate the ozone loss by transport method. Minimum temperatures calculated from ECMWF analyzes over 50-90°S at 475 K are coldest in 2008 during June-July and in 2006 during September-November. In general, Antarctic winters experience NAT temperatures from mid-May to mid-October and ICE temperatures from June to September. Due to the saturation of chemical ozone loss, the year-to-year difference in temperatures do not have a large effect. The estimated cumulative ozone loss from MIMOSA-CHIM at 475 K is 3.2 in 2005, 2.9 in 2006, 2.8 in 2007 and 2.0 ppm in 2008. The measured cumulative loss in the respective years also show similar values: respectively 3.3, 3.2, 2.8 and 2.2 ppm in 2005, 2006, 2007 and 2008. Both data sets show the same loss trend, as the cumulative loss is highest in 2005 followed by 2006 and the lowest in 2008, and are in accord with the chlorine activation and denitrification found in the respective winters. The simulations in 2008 lack adequate diabatic descent as assessed from tracer simulations in comparison with measurements. This eventually produced relatively lower values for ozone loss in 2008 in both data sets even though the observed chlorine activation was found to be similar to previous winters.

Variables affecting efficiency of molasses fermentation wastewater ozonation.

PubMed

Coca, M; Peña, M; González, G

2005-09-01

The main operating variables affecting ozonation efficiencies of wastewater from beet molasses alcoholic fermentation have been studied. Semibatch experiments have been performed in order to analyze the influence of pH, bicarbonate ion, temperature and stirring rate on color and organic matter removals. The efficiencies were similar regardless of the pH, which indicates that direct reactions of ozone with wastewater organics were predominant to radical reactions. Gel permeation chromatography confirmed the reduction in the concentration of organics absorbing light at 475 nm after ozonation. The elimination of bicarbonate ion, strong inhibitor of hydroxyl radical reactions, yielded an improvement in both color and COD reduction efficiencies. Acidification for removing bicarbonate ions produced a shift of colored compounds to smaller molecular weights. The highest efficiencies were achieved at 40 degrees C. Color and COD reductions at 40 degrees C were about 90% and 37%, respectively. In no case, the percentage of TOC removed was higher than 10-15%. Stirring rate had a slightly positive effect during the first stage of the ozonation showing that mass transfer played a role only during the initial reaction phase when direct attack of ozone molecules to aromatic/olefinic structures of colored substances was the predominant pathway.

Radiative effects due to North American anthropogenic and lightning emissions: Global and regional modeling

NASA Astrophysics Data System (ADS)

Martini, Matus Novak

We analyze the contribution of North American (NA) lightning and anthropogenic emissions to summertime ozone concentrations, radiative forcing, and exports from North America using the global University of Maryland chemistry transport model (UMD-CTM) and the regional scale Weather Research and Forecasting model with chemistry (WRF-Chem). Lightning NO contributes by 15--20 ppbv to upper tropospheric ozone concentrations over the United States with the effects of NA lightning on ozone seen as far east as North Africa and Europe. Using the UMD-CTM, we compare changes in surface and column ozone amounts due to the NOx State Implementation Plan (SIP) Call with the natural variability in ozone due to changes in meteorology and lightning. Comparing early summer 2004 with 2002, surface ozone decreased by up to 5 ppbv due to the NO x SIP Call while changes in meteorology and lightning resulted in a 0.3--1.4 ppbv increase in surface ozone. Ozone column variability was driven primarily by changes in lightning NO emissions, especially over the North Atlantic. As part of our WRF-Chem analysis, we modify the radiation schemes to use model-calculated ozone (interactive ozone) instead of climatological ozone profiles and conduct multiple 4-day simulations of July 2007. We found that interactive ozone increased the outgoing longwave radiation (OLR) by 3 W m-2 decreasing the bias with respect to remotely sensed OLR. The improvement is due to a high bias in the climatological ozone profiles. The interactive ozone had a small impact on mean upper troposphere temperature (-0.15°C). The UMD-CTM simulations indicate that NA anthropogenic emissions are responsible for more ozone export but less ozone radiative forcing than lightning NO emissions. Over the North Atlantic, NA anthropogenic emissions contributed 0.15--0.30 W m-2 to the net downward radiative flux at the tropopause while NA lightning contributed 0.30--0.50 W m-2. The ozone export from anthropogenic emissions was almost twice as large as that from lightning emissions. The WRF-Chem simulations show that the export of reactive nitrogen was 23%--28% of the boundary layer emissions and 26%--38% of the total emissions including lightning NO.

Reanalysis of Mariner 9 UV Spectrometer Data for Ozone, Cloud, and Dust Abundances, and Their Interaction Over Climate Timescales

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1994-01-01

Mariner 9 UV spectrometer data have been reinverted for the ozone abundance. The spectra were fit by models which covered the full range in observed solar zenith angle, cloud, dust and ozone amount, ice albedo and look angles. Errors in ozone retrieval with this data are tabulated over a range in theses conditions and are shown graphically. This work shows that significant underestimation of ozone occurred in earlier analysis of Mariner 9 data, and that much of the observed variability in Mars ozone is due to masking of ozone by clouds and dust. An in-situ measurement by balloon is recommended as it is the only technique capable of accurately inferring the ozone abundance in all conditions. Recommendations for future research are also presented. 7 manuscripts have been published in refereed journals, and three are in review. A review of these publications and presentations is in the report.

An assessment of the stray light in 25 years of Dobson total ozone data at Athens, Greece

NASA Astrophysics Data System (ADS)

Christodoulakis, J.; Varotsos, C.; Cracknell, A. P.; Tzanis, C.; Neofytos, A.

2015-07-01

In this study, we investigated the susceptibility of the Dobson spectrophotometer No. 118 to stray light interference. In this regard, a series of total ozone content measurements were carried out in Athens, Greece for air-mass values (μ) extending up to μ = 5. The monochromatic-heterochromatic stray light derived by Basher's model was used in order to evaluate the specific instrumental parameters which determine if this instrument suffers from this problem or not. The results obtained indicate that the measurements made by the Dobson instrument of the Athens station for air mass values up to 2.5, underestimates the total ozone content by 3.5 DU in average, or about 1 % of the station's mean total ozone content (TOC). The comparison of the values of the same parameters measured 15 years ago with the present ones indicates the good maintenance of the Dobson spectrophotometer No. 118. This fact is of crucial importance because the variability of the daily total ozone observations collected by the Athens Dobson Station since 1989 has proved to be representative to the variability of the mean total ozone observed over the whole mid-latitude zone of the Northern Hemisphere. This stresses the point that the Athens total ozone station, being the unique Dobson station in south-eastern Europe, may be assumed as a ground truth station for the reliable conversion of the satellite radiance observations to total ozone measurements.

Global trends

NASA Technical Reports Server (NTRS)

Megie, G.; Chanin, M.-L.; Ehhalt, D.; Fraser, P.; Frederick, J. F.; Gille, J. C.; Mccormick, M. P.; Schoebert, M.; Bishop, L.; Bojkov, R. D.

1990-01-01

Measuring trends in ozone, and most other geophysical variables, requires that a small systematic change with time be determined from signals that have large periodic and aperiodic variations. Their time scales range from the day-to-day changes due to atmospheric motions through seasonal and annual variations to 11 year cycles resulting from changes in the sun UV output. Because of the magnitude of all of these variations is not well known and highly variable, it is necessary to measure over more than one period of the variations to remove their effects. This means that at least 2 or more times the 11 year sunspot cycle. Thus, the first requirement is for a long term data record. The second related requirement is that the record be consistent. A third requirement is for reasonable global sampling, to ensure that the effects are representative of the entire Earth. The various observational methods relevant to trend detection are reviewed to characterize their quality and time and space coverage. Available data are then examined for long term trends or recent changes in ozone total content and vertical distribution, as well as related parameters such as stratospheric temperature, source gases and aerosols.

Characterization of Industrial Emission Sources and Photochemistry in Houston, Texas

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Atlas, E. L.; Degouw, J.; Flocke, F. M.; Fried, A.; Frost, G. J.; Holloway, J.; Richter, D.; Ryerson, T. B.; Schauffler, S.; Trainer, M.; Walega, J.; Warneke, C.; Weibring, P.; Zheng, W.

2009-12-01

The Houston-Galveston urban area contains a number of large industrial petrochemical emission sources that produce volatile organic compounds and nitrogen oxides. These co-located emissions result in rapid and efficient ozone production downwind. Unlike a single large power plant, the industrial complexes consist of numerous sources that can be difficult to quantify in emission inventories. During September - October 2006, the NOAA WP-3 aircraft conducted research flights as part of the second Texas Air Quality Study (TexAQS II). We examine measurements of NOx, SO2, and speciated hydrocarbons from the Houston Ship Channel, which contains a dense concentration of industrial petrochemical sources, and isolated petrochemical facilities. These measurements are used to derive source emission estimates, which are then compared to available emission inventories. We find that high hydrocarbon emissions are typical for the Houston Ship Channel and isolated petrochemical facilities. Ethene and propene are found to be major contributors to ozone formation. Ratios of C2H4 / NOx and C3H6 / NOx exceed emission inventory values by factors of 10 - 50. These findings are consistent with the first TexAQS study in 2000. We examine trends in C2H4 / NOx and C3H6 / NOx ratios between 2000 and 2006, and determine that day-to-day variability and within-plume variability exceeds any long-term reduction in ethene and propene emissions for the isolated petrochemical sources. We additionally examine downwind photochemical products formed by these alkenes.

Science Accomplishments from a Decade of Aura OMI/MLS Tropospheric Ozone Measurements

NASA Technical Reports Server (NTRS)

Ziemke, Jerald R.; Douglass, Anne R.; Joiner, Joanna; Duncan, Bryan N.; Olsen, Mark A.; Oman, Luke D.; Witte, Jacquelyn C.; Liu, X.; Wargan, K.; Schoeberl, Mark R.;

Improvement of OMI Ozone Profile Retrievals in the Troposphere and Lower Troposphere by the Use of the Tropopause-Based Ozone Profile Climatology

NASA Technical Reports Server (NTRS)

Bak, Juseon; Liu, X.; Wei, J.; Kim, J. H.; Chance, K.; Barnet, C.

2011-01-01

An advance algorithm based on the optimal estimation technique has beeen developed to derive ozone profile from GOME UV radiances and have adapted it to OMI UV radiances. OMI vertical resolution : 7-11 km in the troposphere and 10-14 km in the stratosphere. Satellite ultraviolet measurements (GOME, OMI) contain little vertical information for the small scale of ozone, especially in the upper troposphere (UT) and lower stratosphere (LS) where the sharp O3 gradient across the tropopause and large ozone variability are observed. Therefore, retrievals depend greatly on the a-priori knowledge in the UTLS

Some observations on the role of planetary waves in determining the spring time ozone distribution in the Antarctic

NASA Technical Reports Server (NTRS)

Chandra, S.; Mcpeters, R. D.

1986-01-01

Ozone measurements from 1970 to 1984 from the Nimbus 4 backscattered ultraviolet and the Nimbus 7 solar backscattered ultraviolet spectrometers show significant decrease in total ozone only after 1979. The downward trend is most apparent in October south of 70 deg S in the longitude zone 0 to 30 deg W where planetary wave activity is weak. Outside this longitude region, the trend in total ozone is much smaller due to strong interannual variability of wave activity. This paper gives a phenomenological description of ozone depletion in the Antarctic region based on vertical advection and transient planetary waves.

Tropical Tropospheric Ozone: A Multi-Satellite View From TOMS and Other Instruments

NASA Technical Reports Server (NTRS)

Thompson, Anne M.; Hudson, Robert D.; Guo, Hua; Witte, Jacquelyn C.; Kucsera, Tom L.; Seybold, Matthew G.; Einaudi, Franco (Technical Monitor)

2000-01-01

New tropospheric ozone and aerosol products from the TOMS (Total Ozone Mapping Spectrometer) satellite instrument can resolve episodic pollution events in the tropics and interannual and seasonal variability. Modified-residual (MR) Nimbus 7 tropical tropospheric ozone (TTO), two maps/month (1979-1992, 1-deg latitude by 2-deg longitude) within the region in which total ozone displays a tropical wave-one pattern (maximum 20S to 20N), are available in digital form at http://metosrv2.umd.edu/tropo. Also available are preliminary 1996-1999 MR-TTO maps based on real-time Earth-Probe (EP)/TOMS observations. Examples of applications are given.

Evaluation of Intercontinental Transport of Ozone Using Full-tagged, Tagged-N and Sensitivity Methods

NASA Astrophysics Data System (ADS)

Guo, Y.; Liu, J.; Mauzerall, D. L.; Emmons, L. K.; Horowitz, L. W.; Fan, S.; Li, X.; Tao, S.

2014-12-01

Long-range transport of ozone is of great concern, yet the source-receptor relationships derived previously depend strongly on the source attribution techniques used. Here we describe a new tagged ozone mechanism (full-tagged), the design of which seeks to take into account the combined effects of emissions of ozone precursors, CO, NOx and VOCs, from a particular source, while keeping the current state of chemical equilibrium unchanged. We label emissions from the target source (A) and background (B). When two species from A and B sources react with each other, half of the resulting products are labeled A, and half B. Thus the impact of a given source on downwind regions is recorded through tagged chemistry. We then incorporate this mechanism into the Model for Ozone and Related chemical Tracers (MOZART-4) to examine the impact of anthropogenic emissions within North America, Europe, East Asia and South Asia on ground-level ozone downwind of source regions during 1999-2000. We compare our results with two previously used methods -- the sensitivity and tagged-N approaches. The ozone attributed to a given source by the full-tagged method is more widely distributed spatially, but has weaker seasonal variability than that estimated by the other methods. On a seasonal basis, for most source/receptor pairs, the full-tagged method estimates the largest amount of tagged ozone, followed by the sensitivity and tagged-N methods. In terms of trans-Pacific influence of ozone pollution, the full-tagged method estimates the strongest impact of East Asian (EA) emissions on the western U.S. (WUS) in MAM and JJA (~3 ppbv), which is substantially different in magnitude and seasonality from tagged-N and sensitivity studies. This difference results from the full-tagged method accounting for the maintenance of peroxy radicals (e.g., CH3O2, CH3CO3, and HO2), in addition to NOy, as effective reservoirs of EA source impact across the Pacific, allowing for a significant contribution to ozone formation over WUS (particularly in summer). Thus, the full-tagged method, with its clear discrimination of source and background contributions on a per-reaction basis, provides unique insights into the critical role of VOCs (and additional reactive nitrogen species) in determining the nonlinear inter-continental influence of ozone pollution.

Ozone as a Sink for Atmospheric Carbon Aerosols

NASA Astrophysics Data System (ADS)

Stephens, Sherry Lynn

Critical information necessary for examining the chemical removal of smoke in the atmosphere by the reaction with ozone has been obtained. The kinetics, products and temperature dependence of the reaction of ozone with carbonaceous material were determined. This information can be included in models examining the fate of ozone and smoke in the atmosphere. In the first study, the rate of ozone loss was followed in its reaction with carbon black at room temperature. In addition to the ozone loss, the gaseous products, CO, CO _2 and O_2 were quantified with a phase locking mass spectrometer attached to a two-chamber Knudsen cell reactor. An oxygen molecule was detected for every ozone lost. It was observed that the initial loss rate was much greater than that seen after extended exposure to ozone. Oxygen atoms were desorbed 30% of the time as CO or CO_2 and those left behind on the surface were responsible for the decrease in rate. Heating the surface following this exposure would liberate CO and CO_2 and restore the initial reactivity. In the second study, the reaction of ozone with different types of soot was examined by following the decrease of optical depth of soot deposited on a quartz slide as a result of flowing a known concentration of ozone over the slide at temperatures from 21^circ to 175^circC. The reaction kinetics were very similar for the four types of soot used in this study. Treating all types together the activation energy and the order with respect to ozone were 10.9 (+/-1.0) kcal mol ^{-1} and 0.89 (+/- 0.14), respectively. The lifetime of soot under atmospheric conditions was calculated to be on the order of years to decades. The reaction of ozone with acetylene smoke suspended in air was the final method of examining the reaction. The change of acetylene smoke size distribution and ozone concentration was monitored while controlling the temperature. Irreproducibility caused this study to be unsuccessful. This was believed to be due to contamination leaking into the teflon bags in which the experiments were conducted. Several attempts to alleviate this problem were unsuccessful.

Low Ozone over Europe Doesn't Mean the Sky Is Falling, Its Actually Rising

NASA Technical Reports Server (NTRS)

Strahan, Susan; Newman, Paul; Steenrod, Stephen

2016-01-01

Data Sources: NASA Aura Microwave Limb Sounder (MLS) (O3 profiles and columns), NASA Global Modeling Initiative (GMI) Chemistry and Transport Model (calculated O3depletion), and MERRA Tropopause Heights. Technical Description of Figures: The left graphics show MLS northern hemisphere stratospheric column ozone on Feb. 1, 2016. Very low columns are seen over the UK and Europe (<225 DU, inside dashed circle). The lower graphic shows the GMI-calculated O3 depletion. It's very small, suggesting the low O3 does not indicate significant depletion. The right graphics show how the high tropopause height in this region explains the observed low ozone. The lower panel shows that the high tropopause on Feb. 1 lifts the O3 profile compared to a typical profile found earlier in winter. This motion lifts the profile to lower pressures thus reducing the total column. The GMI Model shows only 4 Dobson Units (DU) of O3 depletion even though the column is more than 100 DU lower than one month earlier. Scientific significant and societal relevance: To quantitatively understand anthropogenic impacts to the stratospheric ozone layer, we must be able to distinguish between low ozone caused by ozone depleting substances and that caused by natural dynamical variability in the atmosphere. Observations and realistic simulations of atmospheric composition are both required in order to separate natural and anthropogenic ozone variability.

Meteorological air quality forecasting using the WRF-Chem model during the LMOS2017 field campaign

NASA Astrophysics Data System (ADS)

Stanier, C. O.; Abdioskouei, M.; Carmichael, G. R.; Christiansen, M.; Sobhani, N.

2017-12-01

The Lake Michigan Ozone Study (LMOS 2017) occurred during May and June 2017 to address the high ozone episodes in coastal communities surrounding Lake Michigan. Aircraft, ship, mobile lab, and ground-based stations were used in this campaign to build an extensive dataset regarding ozone, its precursors, and particulate matter. The University of Iowa produced high-resolution (4x4 km2 horizontal resolution and 53 vertical levels) forecast products using the WRF-Chem modeling system in support of experimental planning during LMOS 2017. The base forecast system used WRF-Chem 3.6.1 and updated National Emission Inventory (NEI-2011v2). In the updated NEI-2011v2, we reduced the NOx emissions by 28% based on EPA's estimated NOx trends from 2011 to 2017. We ran another daily forecast (perturbed forecast) with 50% reduced NOx emission to capture the sensitivity of ozone to NOx emission and account for the impact of weekend emissions on ozone values. Preliminary in-field evaluation of model performance for clouds, on-shore flows, and surface and aircraft sampled ozone and NOx concentrations found that the model successfully captured much of the observed synoptic variability of onshore flows. The model captured the variability of O3 well, but underpredicted peak ozone during high O3 episodes. In post-campaign WRF-Chem simulations, we investigated the sensitivity of the model to the hydrocarbon emission.

Regional and hemispheric influences on temporal variability in baseline carbon monoxide and ozone over the Northeast US

NASA Astrophysics Data System (ADS)

Zhou, Y.; Mao, H.; Demerjian, K.; Hogrefe, C.; Liu, J.

2017-09-01

Interannual variability in baseline carbon monoxide (CO) and ozone (O3), defined as mixing ratios under minimal influence of recent and local emissions, was studied for seven rural sites in the Northeast US over 2001-2010. Annual baseline CO exhibited statistically significant decreasing trends (-4.3 to -2.3 ppbv yr-1), while baseline O3 did not display trends at any site. In examining the data by season, wintertime and springtime baseline CO at the two highest sites (1.5 km and 2 km asl) did not experience significant trends. Decadal increasing trends (∼2.55 ppbv yr-1) were found in springtime and wintertime baseline O3 in southern New Hampshire, which was associated with anthropogenic NOx emission reductions from the urban corridor. Biomass burning emissions impacted summertime baseline CO with ∼38% variability from wildfire emissions in Russia and ∼22% from Canada at five sites and impacted baseline O3 at the two high elevation sites only with ∼27% variability from wildfires in both Russia and Canada. The Arctic Oscillation was negatively correlated with summertime baseline O3, while the North Atlantic Oscillation was positively correlated with springtime baseline O3. This study suggested that anthropogenic and biomass burning emissions, and meteorological conditions were important factors working together to determine baseline O3 and CO in the Northeast U.S. during the 2000s.

An extreme anomaly in stratospheric ozone over Europe in 1940-1942

NASA Astrophysics Data System (ADS)

Brönnimann, S.; Luterbacher, J.; Staehelin, J.; Svendby, T. M.

2004-04-01

Reevaluated historical total ozone data reveal extraordinarily high values over several European sites in 1940-1942, concurrent with extreme climatic anomalies at the Earth's surface. Using historical radiosonde data, reconstructed upper-level fields, and total ozone data from Arosa (Switzerland), Dombås, and Tromsø (Norway), this unusual case of stratosphere-troposphere coupling is analyzed. At Arosa, numerous strong total ozone peaks in all seasons were due to unusually frequent upper troughs over central Europe and related ozone redistribution in the lower stratosphere. At the Norwegian sites, high winter total ozone was most likely caused by major stratospheric warmings in Jan./Feb. 1940, Feb./Mar. 1941, and Feb. 1942. Results demonstrate that the dynamically driven interannual variability of total ozone can be much larger than that estimated based on the past 25-40 years.

Tropospheric Ozone and Biomass Burning

NASA Astrophysics Data System (ADS)

Chandra, S.; Ziemke, J. R.; Bhartia, P. K.

2001-05-01

This paper studies the significance of pyrogenic (e.g., biomass burning) emissions in the production of tropospheric ozone in the tropics associated with the forest and savanna fires in the African, South American, and Indonesian regions. Using aerosol index (AI) and tropospheric column ozone (TCO) time series from 1979 to 2000 derived from the Nimbus-7 and Earth Probe TOMS measurements, our study shows significant differences in the seasonal and spatial characteristics of pyrogenic emissions north and south of the equator in the African region and Brazil in South America. In general, they are not related to the seasonal and spatial characteristics of tropospheric ozone in these regions. In the Indonesian region, the most significant increase in TCO occurred during September and October 1997, following large-scale forest and savanna fires associated with the El Niño-induced dry condition. However, the increase in TCO extended over most of the western Pacific well outside the burning region and was accompanied by a decrease in the eastern Pacific resembling a west-to-east dipole about the dateline. The net increase in TCO integrated over the tropical region between 15N and 15S was about 6-8 Tg (terragram) over the mean climatological value of about 72 Tg. This increase is within the range of interannual variability of TCO in the tropical region and does not necessarily suggest a photochemical source related to biomass burning. The interannual variability in TCO appears to be out of phase with the interannual variability of stratospheric column ozone (SCO). These variabilities seem to be manifestations of solar cycle and quasi-biennial oscillations.

Tropospheric Ozone and Biomass Burning

NASA Technical Reports Server (NTRS)

Chandra, Sushil; Ziemke, J. R.; Bhartia, P. K.; Einaudi, Franco (Technical Monitor)

2001-01-01

This paper studies the significance of pyrogenic (e.g., biomass burning) emissions in the production of tropospheric ozone in the tropics associated with the forest and savanna fires in the African, South American, and Indonesian regions. Using aerosol index (Al) and tropospheric column ozone (TCO) time series from 1979 to 2000 derived from the Nimbus-7 and Earth Probe TOMS measurements, our study shows significant differences in the seasonal and spatial characteristics of pyrogenic emissions north and south of the equator in the African region and Brazil in South America. In general, they are not related to the seasonal and spatial characteristics of tropospheric ozone in these regions. In the Indonesian region, the most significant increase in TCO occurred during September and October 1997, following large-scale forest and savanna fires associated with the El Nino-induced dry season. However, the increase in TCO extended over most of the western Pacific well outside the burning region and was accompanied by a decrease in the eastern Pacific resembling a west-to-east dipole about the date-line. The net increase in TCO integrated over the tropical region between 15 deg N and 15 deg S was about 6-8 Tg (1 Tg = 10(exp 12) gm) over the mean climatological value of about 72 Tg. This increase is well within the range of interannual variability of TCO in the tropical region and does not necessarily suggest a photochemical source related to biomass burning. The interannual variability in TCO appears to be out of phase with the interannual variability of stratospheric column ozone (SCO). These variabilities seem to be manifestations of solar cycle and quasibiennial oscillations.

The search for signs of recovery of the ozone layer.

PubMed

Weatherhead, Elizabeth C; Andersen, Signe Bech

2006-05-04

Evidence of mid-latitude ozone depletion and proof that the Antarctic ozone hole was caused by humans spurred policy makers from the late 1980s onwards to ratify the Montreal Protocol and subsequent treaties, legislating for reduced production of ozone-depleting substances. The case of anthropogenic ozone loss has often been cited since as a success story of international agreements in the regulation of environmental pollution. Although recent data suggest that total column ozone abundances have at least not decreased over the past eight years for most of the world, it is still uncertain whether this improvement is actually attributable to the observed decline in the amount of ozone-depleting substances in the Earth's atmosphere. The high natural variability in ozone abundances, due in part to the solar cycle as well as changes in transport and temperature, could override the relatively small changes expected from the recent decrease in ozone-depleting substances. Whatever the benefits of the Montreal agreement, recovery of ozone is likely to occur in a different atmospheric environment, with changes expected in atmospheric transport, temperature and important trace gases. It is therefore unlikely that ozone will stabilize at levels observed before 1980, when a decline in ozone concentrations was first observed.

Quantifying Chemical Ozone Loss in the Arctic Stratosphere with GEOS-STRATCHEM Data Assimilation System

NASA Technical Reports Server (NTRS)

Wargan, K.; Nielsen, J. E.

2017-01-01

A faithful representation of polar stratospheric chemistry in models and its connection with dynamical variability is essential for our understanding of the evolution of the ozone layer in a changing climate and during the projected continuing decline of ozone depleting substances in the atmosphere. We use a new configuration of the Goddard Earth Observing System Data Assimilation System with a stratospheric chemistry model to study ozone depletion in the Arctic polar stratosphere during the exceptionally cold (in the stratosphere) winters 2015/2016 and 2010/2011.

Global Distribution and Trends of Tropospheric Ozone: An Observation-Based Review

NASA Technical Reports Server (NTRS)

Cooper, O. R.; Parrish, D. D.; Ziemke, J.; Cupeiro, M.; Galbally, I. E.; Gilge, S.; Horowitz, L.; Jensen, N. R.; Lamarque, J.-F.; Naik, V.;

Evaluation of the stomatal conductance formulation in the EMEP ozone deposition model for Picea abies

NASA Astrophysics Data System (ADS)

Wieser, G.; Emberson, L. D.

It is widely acknowledged that the possible impacts of ozone on forest trees are more closely related to ozone flux through the stomata than to external ozone exposure. However, the application of the flux approach on a European scale requires the availability of appropriate models, such as the European Monitoring and Evaluation Programme (EMEP) ozone deposition model, for estimating ozone flux and cumulative ozone uptake. Within this model stomatal conductance is the key variable, since it determines the amount of ozone absorbed by the leaves. This paper describes the suitability of the existing EMEP ozone deposition model parameterisation and formulation to represent stomatal behaviour determined from field measurements on adult Norway spruce ( Picea abies (L.) Karst.) trees in the Central European Alps. Parameters affecting maximum stomatal conductance (e.g. seasonal phenology, needle position, needle age, nutrient deficiency and ozone itself) and stomatal response functions to temperature, irradiance, vapour pressure deficit, and soil water content are investigated. Finally, current limitations and possible alterations of the EMEP model will be discussed with respect to spatial scales of available input data for future flux modelling.

Tropospheric Ozone during the TRACE-P Mission: Comparison between TOMS Satellite Retrievals and Aircraft Lidar Data, March 2001

NASA Technical Reports Server (NTRS)

Frolov, A. D.; Thompson, A. M.; Hudson, R. D.; Browell, E. V.; Oltmans, S. J.; Witte, J. C.; Bhartia, P. K. (Technical Monitor)

2002-01-01

Over the past several years, we have developed two new tropospheric ozone retrievals from the TOMS (Total Ozone Mapping Spectrometer) satellite instrument that are of sufficient resolution to follow pollution episodes. The modified-residual technique uses v. 7 TOMS total ozone and is applicable to tropical regimes in which the wave-one pattern in total ozone is observed. The TOMS-direct method ('TDOT' = TOMS Direct Ozone in the Troposphere) represents a new algorithm that uses TOMS radiances directly to extract tropospheric ozone in regions of constant stratospheric ozone. It is not geographically restricted, using meteorological regimes as the basis for classifying TOMS radiances and for selecting appropriate comparison data. TDOT is useful where tropospheric ozone displays high mixing ratios and variability characteristic of pollution. Some of these episodes were observed downwind of Asian biomass burning during the TRACE-P (Transport and Atmospheric Chemical Evolution-Pacific) field experiment in March 2001. This paper features comparisons among TDOT tropospheric ozone column depth, integrated uv-DIAL measurements made from NASA's DC-8, and ozonesonde data.

Impacts of seasonal and regional variability in biogenic VOC emissions on surface ozone in the Pearl River Delta region, China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Situ, S.; Guenther, Alex B.; Wang, X. J.

In this study, the BVOC emissions in November 2010 over the Pearl River Delta (PRD) region in southern China have been estimated by the latest version of a Biogenic Volatile Organic Compound (BVOC) emission model (MEGAN v2.1). The evaluation of MEGAN performance at a representative forest site within this region indicates MEGAN can estimate BVOC emissions reasonably well in this region except overestimating isoprene emission in autumn for reasons that are discussed in this manuscript. Along with the output from MEGAN, the Weather Research and Forecasting model with chemistry (WRF-Chem) is used to estimate the impacts of BVOC emissions onmore » surface ozone in the PRD region. The results show BVOC emissions increase the daytime ozone peak by *3 ppb on average, and the max hourly impacts of BVOC emissions on the daytime ozone peak is 24.8 ppb. Surface ozone mixing ratios in the central area of Guangzhou- Foshan and the western Jiangmen are most sensitive to BVOC emissions BVOCs from outside and central PRD influence the central area of Guangzhou-Foshan and the western Jiangmen significantly while BVOCs from rural PRD mainly influence the western Jiangmen. The impacts of BVOC emissions on surface ozone differ in different PRD cities, and the impact varies in different seasons. Foshan and Jiangmen being most affected in autumn, result in 6.0 ppb and 5.5 ppb increases in surface ozone concentrations, while Guangzhou and Huizhou become more affected in summer. Three additional experiments concerning the sensitivity of surface ozone to MEGAN input variables show that surface ozone is more sensitive to landcover change, followed by emission factors and meteorology.« less

Ground-based total ozone column measurements and their diurnal variability

NASA Astrophysics Data System (ADS)

Silva, Abel A.

2013-07-01

Brewer spectrophotometers were set up in three tropical sites of South America (in the Bolivian Altiplano and seashore and biomass burning areas of Brazil) to measure the total ozone column (TOC). Only TOC measurements with uncertainties ≤1% (1σ) were considered. Typically, the standard deviation for the diurnal sets of measurements was predominantly ≤1% for two of these sites. The average variability in TOC ranged from 6.3 Dobson units (DU) to 16.8 DU, and the largest variability reached 54.3 DU. Comparisons between ground-based and satellite (Total Ozone Mapping Spectrometer (TOMS)) data showed good agreement with coefficients of determination ≤0.83. However, the quality of the ground-based measurements was affected by the weather condition, especially for one of the sites. Visual observation of the sky from the ground during the measurements with one of the Brewers added to the satellite data of reflectivity and aerosol index supports that statement.

HYDROXYL RADICAL/OZONE RATIOS DURING OZONATION PROCESSES. I. THE RCT CONCEPT

EPA Science Inventory

The ozonation of model systems and several natural waters was examined in bench-scale batch experiments. In addition to measuring the concentration of ozone (03), the rate of depletion of an in situ hydroxyl radical probe compound was monitored, thus providing information on the ...

An observational study of the ozone dilution effect: Ozone transport in the austral spring stratosphere

NASA Technical Reports Server (NTRS)

Atkinson, Roger J.; Plumb, R. Alan

1994-01-01

In a previous observational analysis, Atkinson et al (1989) ascribed a sudden decrease in Southern Hemisphere midlatitude total ozone during December 1987 to an 'ozone dilution effect' brought about by the breakup of the polar stratospheric vortex at that time. A question alluded to but unanswered by that study was the degree to which the observed total ozone decrease might have been caused by the quasi-horizontal equatorward transport of 'ozone hold' air from within the vortex, and to what degree by the vertical advection from lower levels of air naturally low in ozone, a dynamical adjustment process which must accompany the equatorward outbreak of a discrete high-latitude airmass. In the present study, analyses of Ertel potential vorticity, TOMS total ozone, and SAGE and ozone sonde vertical profile data are employed using a novel technique to examine the 1987 event in greater detail, to answer this question. Recent progress is then reported in refining the technique and extending the investigation to examine the dynamical evolution of the austral spring stratosphere during other recent years, to shed more light on the precise nature, frequency, and severity of such 'ozone dilution' events, and the effect that this process may have on long term ozone behavior in the Southern Hemisphere.

Ozone Lidar Observations for Air Quality Studies

NASA Technical Reports Server (NTRS)

Wang, Lihua; Newchurch, Mike; Kuang, Shi; Burris, John F.; Huang, Guanyu; Pour-Biazar, Arastoo; Koshak, William; Follette-Cook, Melanie B.; Pickering, Kenneth E.; McGee, Thomas J.;

Detection and measurement of total ozone from stellar spectra: Paper 2. Historic data from 1935 1942

NASA Astrophysics Data System (ADS)

Griffin, R. E. M.

2005-10-01

Atmospheric ozone columns are derived from historic stellar spectra observed between 1935 and 1942 at Mount Wilson Observatory, California. Comparisons with contemporary measurements in the Arosa database show a generally close correspondence. The results of the analysis indicate that astronomy's archives command considerable potential for investigating the natural levels of ozone and its variability during the decades prior to anthropogenic interference.

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.

An assessment of the stray-light in 25 years Dobson total ozone data at Athens, Greece

NASA Astrophysics Data System (ADS)

Christodoulakis, J.; Varotsos, C.; Cracknell, A. P.; Tzanis, C.; Neofytos, A.

2015-02-01

In this study, we investigated the susceptibility of the Dobson spectrophotometer No. 118 to stray-light interference. In this regard, a series of total ozone content measurements were carried out in Athens, Greece for airmass values (μ) extending up to μ = 5. The monochromatic-heterochromatic stray-light derived by Basher's model was used in order to evaluate the specific instrumental parameters which determine if this instrument suffers from this problem or not. The results obtained indicate that the Athens Dobson instrument appears to have an insignificant stray-light error. The comparison of the values of the same parameters measured 15 years ago with the present ones indicates the good maintenance of the Dobson spectrophotometer No. 118. This fact is of crucial importance because the variability of the daily total ozone observations collected by the Athens Dobson Station since 1989 has proved to be representative to the variability of the mean total ozone observed over the whole mid-latitude zone of the Northern Hemisphere. This stresses the point that the Athens total ozone station, being the unique Dobson station in south eastern Europe, may be assumed as a ground-truth station for the reliable conversion of the satellite radiance observations to total ozone measurements.

Regional Differences in Stratospheric Intrusions over the USA Investigated using the NASA MERRA-2 Reanalysis

NASA Astrophysics Data System (ADS)

Knowland, K. E.; Ott, L.; Hodges, K.; Wargan, K.; Duncan, B. N.

2016-12-01

Stratospheric intrusions (SI) - the introduction of ozone-rich stratospheric air into the troposphere - have been linked with surface ozone air quality exceedences, especially at the high elevations in the western USA in springtime. However, the impact of SIs in the remaining seasons and over the rest of the USA is less clear. This study investigates the atmospheric dynamics that generate SIs over the western USA and the different mechanisms through which SIs may influence atmospheric chemistry and surface air quality over the eastern USA. An analysis of the spatiotemporal variability of SIs over the continental US is performed using NASA's Modern-Era Retrospective Analysis for Research and Applications Version-2 (MERRA-2) reanalysis dataset and other Goddard Earth Observing System Model, Version 5 (GEOS-5) model products. Both upper-level and lower-level dynamical features are examined on seasonal timescales using the tracking algorithm of Hodges (1995, 1999). We show how upper-level relative vorticity maxima - representing troughs and cut-off lows - can be tracked and related to the lower-level storm tracks. The influence of both sets of tracks on the assimilated MERRA-2 ozone and meteorological parameters throughout the troposphere and lower stratosphere is quantified. By focusing on the major modes of variability that influence the weather patterns in the USA, namely the Pacific North American (PNA) pattern, Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO), predicative patterns in the meteorological fields that are associated with SIs are identified for their regional effects.

Total ozone changes over Eurasia since 1973 based on reevaluated filter ozonometer data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bojkov, R.D.; Fioletov, V.E.; Shalamjansky, A.M.

1994-11-01

Since the early 1960s, on the vast territory of the former USSR, 45 stations have been in continuous operation, utilizing the broadband filter M-83 ozonometer. The quality of the ozone data during the first decade was unsatisfactory. After 1972 an improved version of the ozonometer was introduced together with improved quality control practices, including methodology of observations. The more reliable data of 1973 through March 1994 have been rigorously reexamined by applying variability analysis, comparison with lower-stratosphere temperatures and/or nearby Dobson stations, and overpassing Total Ozone Mapping Spectrometer (TOMS) for identifying concurrence or discrepancies. These control procedures together with themore » information on instrument relocation and calibrations made it possible to reevaluate the record of all 45 stations. The accuracy of the improved ozonometer data is about 3% for direct Sun measurements and approximately 5% for zenith sky observations; although not so good as that of the Dobson, in the long run it provides consistent ozone data sets. This data set is now made available to the World Ozone Data Center (WO3DC), Toronto. Thus for the first time, based on a 21-year long record, information is deduced on the differences in the ozone annual cycle between Eastern Siberia and the European part, on the strong appearance of quasi-biennial oscillation (QBO) signals especially pronounced as ozone deficiency during the western phase of the QBO, on the ozone variability, and on the long-term changes over the huge territory from Central Europe to the Far East.« less

PARAMETER EVALUATION AND MODEL VALIDATION OF OZONE EXPOSURE ASSESSMENT USING HARVARD SOUTHERN CALIFORNIA CHRONIC OZONE EXPOSURE STUDY DATA

EPA Science Inventory

To examine factors influencing long-term ozone exposures by children living in urban communities, we analyzed longitudinal data on personal, indoor, and outdoor ozone concentrations as well as related housing and other questionnaire information collected in the one-year-long Harv...

Impact of enhanced ozone deposition and halogen chemistry on tropospheric ozone over the Northern Hemisphere

EPA Science Inventory

Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen ch...

A search for relativistic electron induced stratospheric ozone depletion

NASA Technical Reports Server (NTRS)

Aikin, Arthur C.

1994-01-01

Possible ozone changes at 1 mb associated with the time variation and precipitation of relativistic electrons are investigated by examining the NIMBUS 7 SBUV ozone data set and corresponding temperatures derived from NMC data. No ozone depletion was observed in high-latitude summer when temperature fluctuations are small. In winter more variation in ozone occurs, but large temperature changes make it difficult to identify specific ozone decreases as being the result of relativistic electron precipitation.

Ozone Pollution, Transport and Variability: Examples from Satellite and In-Situ Observations

NASA Technical Reports Server (NTRS)

Thompson, Anne

2003-01-01

Regional and intercontinental transport of ozone has been observed from satellite, aircraft and sounding data. Over the past several years, we have developed new tropospheric ozone retrieval techniques from the TOMS (Total Ozone Mapping Spectrometer) satellite instrument that are of sufficient resolution to follow pollution episodes. The modified-residual technique uses Level 2 total ozone and was used to follow the 1997 fires in the wake of the El-Nino-related fires in southeast Asia and the Indonesian maritime continent. The TOMS-direct method ('TDOT' = TOMS Direct Ozone in the Troposphere) is a newer algorithm that uses TOMS radiances directly to extract tropospheric ozone. Ozonesonde data that have been taken in campaigns (e.g. TRACE-P) and more consistently in the SHADOZ (Southern Hemisphere Additional Ozonesondes) project, reveal layers of pollution traceable with trajectories. Examples will be shown of long-range transport and recirculation over Africa during SAFARI-2000.

Climate variability modulates western US ozone air quality in spring via deep stratospheric intrusions

PubMed Central

Lin, Meiyun; Fiore, Arlene M.; Horowitz, Larry W.; Langford, Andrew O.; Oltmans, Samuel J.; Tarasick, David; Rieder, Harald E.

2015-01-01

Evidence suggests deep stratospheric intrusions can elevate western US surface ozone to unhealthy levels during spring. These intrusions can be classified as ‘exceptional events', which are not counted towards non-attainment determinations. Understanding the factors driving the year-to-year variability of these intrusions is thus relevant for effective implementation of the US ozone air quality standard. Here we use observations and model simulations to link these events to modes of climate variability. We show more frequent late spring stratospheric intrusions when the polar jet meanders towards the western United States, such as occurs following strong La Niña winters (Niño3.4<−1.0 °C). While El Niño leads to enhancements of upper tropospheric ozone, we find this influence does not reach surface air. Fewer and weaker intrusion events follow in the two springs after the 1991 volcanic eruption of Mt. Pinatubo. The linkage between La Niña and western US stratospheric intrusions can be exploited to provide a few months of lead time during which preparations could be made to deploy targeted measurements aimed at identifying these exceptional events. PMID:25964012

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.

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.

Ozone distribution in remote ecologically vulnerable terrain of the southern Sierra Nevada, CA.

PubMed

Panek, Jeanne; Saah, David; Esperanza, Annie; Bytnerowicz, Andrzej; Fraczek, Witold; Cisneros, Ricardo

2013-11-01

Ozone concentration spatial patterns remain largely uncharacterized across the extensive wilderness areas of the Sierra Nevada, CA, despite being downwind of major pollution sources. These natural areas, including four national parks and four national forests, contain forest species that are susceptible to ozone injury. Forests stressed by ozone are also more vulnerable to other agents of mortality, including insects, pathogens, climate change, and ultimately fire. Here we analyze three years of passive ozone monitor data from the southern Sierra Nevada and interpolate landscape-scale spatial and temporal patterns during the summer-through-fall high ozone concentration period. Segmentation analysis revealed three types of ozone exposure sub-regions: high, low, and variable. Consistently high ozone exposure regions are expected to be most vulnerable to forest mortality. One high exposure sub-region has been documented elsewhere as being further vulnerable to increased drought and fire potential. Identifying such hot-spots of forest vulnerability has utility for prioritizing management. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dynamical component of seasonal and year-to-year changes in Antarctic and global ozone

NASA Technical Reports Server (NTRS)

Tung, Ka Kit; Yang, HU

1988-01-01

The dynamics of the ozone concetration components of the Antarctic ozone hole as related to seasonal and year-to-year temperature changes in August, September, October, and November during the 1979-1985 period is studied using a zonally averaged model in which all transport fields are fixed by input temperature data. The results suggest that, prior to 1984, both the seasonal and year-to year variability of the zonal-mean Antarctic ozone minimum and the surrounding maximum can be accounted for by temperature dynamics without invoking changes in chemical composition (e.g., chlorine content) or special chemistry. The same dynamical mechanism also accounts for the good simulation of the observed seasonal and latitudinal structure of column ozone in other parts of the world. However, chemical depletion of ozone may have become more important after 1984. The model also appears to underpredict the September ozone decline in years, leading to an underprediction of the recent minimum values in the Antarctic ozone hole.

A Madden-Julian Oscillation in Tropospheric Ozone

NASA Technical Reports Server (NTRS)

Ziemke, J. R.; Chandra, S.

2004-01-01

This is the first study to indicate a Madden-Julian Oscillation (MJO) in tropospheric ozone. Tropospheric ozone is derived using differential measurements of total column ozone and stratospheric column ozone measured from total ozone mapping spectrometer (TOMS) and microwave limb sounder (MLS) instruments. Two broad regions of significant MJO signal are identified in the tropics, one in the western Pacific and the other in the eastern Pacific. Over both regions, MJO variations in tropospheric ozone represent 5- 10 DU peak-to-peak anomalies. These variations are significant compared to mean background amounts of 20 DU or less over most of the tropical Pacific. The implications of these results are: (1) model values of TCO in the tropical Pacific region, when accounted for the MJO may be highly variable depending upon the phase of the MJO, and (2) MJO signals of this magnitude would need to be considered when investigating and interpreting particular pollution events since ozone is a precursor of the hydroxyl (OH) radical, the main oxidizing agent of pollutants in the lower atmosphere.

Chemical Composition and Dynamics of the Upper Troposphere and the Lower Stratosphere: Overview of the Project

NASA Astrophysics Data System (ADS)

Sofieva, V. F.; Liu, C.; Huang, F.; Kyrola, E.; Liu, Y.; Ialongo, I.; Hakkarainen, J.; Zhang, Y.

2016-08-01

The DRAGON-3 cooperation study on the upper troposphere and the lower stratosphere (UTLS) is based on new satellite data and modern atmospheric models. The objectives of the project are: (i) assessment of satellite data on chemical composition in UTLS, (ii) dynamical and chemical structures of the UTLS and its variability, (iii) multi-scale variability of stratospheric ozone, (iv) climatology of the stratospheric aerosol layer and its variability, and (v) updated ozone climatology and its relation to tropopause/multiple tropopauses.In this paper, we present the main results of the project.

Seasonal and species-specific response of VOC emissions by Mediterranean woody plant to elevated ozone concentrations

NASA Astrophysics Data System (ADS)

Llusià, J.; Peñuelas, J.; Gimeno, B. S.

Although certain factors controlling plant emission rates of volatile organic compounds (VOCs) are reasonably well understood, the influence of elevated ozone concentrations as abiotic stress is mostly unknown. Therefore, we studied the effects of ozone concentrations on seasonal biogenic volatile organic compound (BVOC) emissions by different Mediterranean plant species in open top chambers (OTC). Three ozone treatments were established: filtered air (F), non-filtered air (NF), and fumigated air (NF+) adding 40 nl l -1 of ozone over NF. We studied the response of VOC emission in saplings of four Mediterranean woody plant species and subspecies: Ceratonia siliqua L., Olea europaea L., Quercus ilex spp. ilex L., and Quercus ilex spp. rotundifolia L. as representative of natural Mediterranean vegetation. No visible symptoms were detected on the leaves. No significant effect was found on net photosynthetic rates or stomatal conductance except for an increase in net photosynthetic rates in Quercus ilex ilex in spring and summer and an overall slight increase in Quercus ilex rotundifolia. Emissions of the total VOCs from Ceratonia siliqua in summer, and from Olea europaea and Quercus ilex rotundifolia in spring increased in ozone fumigated OTC in comparison with F or NF OTC. Decreased emissions were found in Quercus ilex rotundifolia in summer. There were no significant differences between ozone fumigation treatments for the other plant species and seasons. When considering particular VOCs, the results were also variable among species and time of the year. While α-pinene emissions decreased with ozone fumigation in Olea europaea, α-pinene and limonene emissions increased in Quercus ilex ilex. The responses of these particular VOCs did not always match the responses of total VOCs. In spite of this strong variability, when considering overall annual data for all species and seasons, there were increased net photosynthetic rates (37%) and limonene (95%) and total VOC (45%) emission rates in ozone-fumigated plants, whereas stomatal conductance did not change. Since VOCs are precursors of ozone, the increase in BVOC emission as a consequence of elevated tropospheric ozone concentrations may lead to positive feedback mechanisms in ozone formation.

Investigating Dry Deposition of Ozone to Vegetation

NASA Astrophysics Data System (ADS)

Silva, Sam J.; Heald, Colette L.

2018-01-01

Atmospheric ozone loss through dry deposition to vegetation is a critically important process for both air quality and ecosystem health. The majority of atmospheric chemistry models calculate dry deposition using a resistance-in-series parameterization by Wesely (1989), which is dependent on many environmental variables and lookup table values. The uncertainties contained within this parameterization have not been fully explored, ultimately challenging our ability to understand global scale biosphere-atmosphere interactions. In this work, we evaluate the GEOS-Chem model simulation of ozone dry deposition using a globally distributed suite of observations. We find that simulated daytime deposition velocities generally reproduce the magnitude of observations to within a factor of 1.4. When correctly accounting for differences in land class between the observations and model, these biases improve, most substantially over the grasses and shrubs land class. These biases do not impact the global ozone burden substantially; however, they do lead to local absolute changes of up to 4 ppbv and relative changes of 15% in summer surface concentrations. We use MERRA meteorology from 1979 to 2008 to assess that the interannual variability in simulated annual mean ozone dry deposition due to model input meteorology is small (generally less than 5% over vegetated surfaces). Sensitivity experiments indicate that the simulation is most sensitive to the stomatal and ground surface resistances, as well as leaf area index. To improve ozone dry deposition models, more measurements are necessary over rainforests and various crop types, alongside constraints on individual depositional pathways and other in-canopy ozone loss processes.

Assimilation of MLS and OMI Ozone Data

NASA Technical Reports Server (NTRS)

Stajner, I.; Wargan, K.; Chang, L.-P.; Hayashi, H.; Pawson, S.; Froidevaux, L.; Livesey, N.

2005-01-01

Ozone data from Aura Microwave Limb Sounder (MLS) and Ozone Monitoring Instrument (OMI) were assimilated into the ozone model at NASA's Global Modeling and Assimilation Office (GMAO). This assimilation produces ozone fields that are superior to those from the operational GMAO assimilation of Solar Backscatter Ultraviolet (SBUV/2) instrument data. Assimilation of Aura data improves the representation of the "ozone hole" and the agreement with independent Stratospheric Aerosol and Gas Experiment (SAGE) III and ozone sonde data. Ozone in the lower stratosphere is captured better: mean state, vertical gradients, spatial and temporal variability are all improved. Inclusion of OMI and MLS data together, or separately, in the assimilation system provides a way of checking how consistent OMI and MLS data are with each other, and with the ozone model. We found that differences between OMI total ozone column data and model forecasts decrease after MLS data are assimilated. This indicates that MLS stratospheric ozone profiles are consistent with OMI total ozone columns. The evaluation of error characteristics of OMI and MLS ozone will continue as data from newer versions of retrievals becomes available. We report on the initial step in obtaining global assimilated ozone fields that combine measurements from different Aura instruments, the ozone model at the GMAO, and their respective error characteristics. We plan to use assimilated ozone fields in estimation of tropospheric ozone. We also plan to investigate impacts of assimilated ozone fields on numerical weather prediction through their use in radiative models and in the assimilation of infrared nadir radiance data from NASA's Advanced Infrared Sounder (AIRS).

Large scale variability, long-term trends and extreme events in total ozone over the northern mid-latitudes based on satellite time series

NASA Astrophysics Data System (ADS)

Rieder, H. E.; Staehelin, J.; Maeder, J. A.; Ribatet, M.; Davison, A. C.

2009-04-01

Various generations of satellites (e.g. TOMS, GOME, OMI) made spatial datasets of column ozone available to the scientific community. This study has a special focus on column ozone over the northern mid-latitudes. Tools from geostatistics and extreme value theory are applied to analyze variability, long-term trends and frequency distributions of extreme events in total ozone. In a recent case study (Rieder et al., 2009) new tools from extreme value theory (Coles, 2001; Ribatet, 2007) have been applied to the world's longest total ozone record from Arosa, Switzerland (e.g. Staehelin 1998a,b), in order to describe extreme events in low and high total ozone. Within the current study this analysis is extended to satellite datasets for the northern mid-latitudes. Further special emphasis is given on patterns and spatial correlations and the influence of changes in atmospheric dynamics (e.g. tropospheric and lower stratospheric pressure systems) on column ozone. References: Coles, S.: An Introduction to Statistical Modeling of Extreme Values, Springer Series in Statistics, ISBN:1852334592, Springer, Berlin, 2001. Ribatet, M.: POT: Modelling peaks over a threshold, R News, 7, 34-36, 2007. Rieder, H.E., Staehelin, J., Maeder, J.A., Ribatet, M., Stübi, R., Weihs, P., Holawe, F., Peter, T., and Davison, A.C.: From ozone mini holes and mini highs towards extreme value theory: New insights from extreme events and non stationarity, submitted to J. Geophys. Res., 2009. Staehelin, J., Kegel, R., and Harris, N. R.: Trend analysis of the homogenized total ozone series of Arosa (Switzerland), 1929-1996, J. Geophys. Res., 103(D7), 8389-8400, doi:10.1029/97JD03650, 1998a. Staehelin, J., Renaud, A., Bader, J., McPeters, R., Viatte, P., Hoegger, B., Bugnion, V., Giroud, M., and Schill, H.: Total ozone series at Arosa (Switzerland): Homogenization and data comparison, J. Geophys. Res., 103(D5), 5827-5842, doi:10.1029/97JD02402, 1998b.

Climate impact of idealized winter polar mesospheric and stratospheric ozone losses as caused by energetic particle precipitation

NASA Astrophysics Data System (ADS)

Meraner, Katharina; Schmidt, Hauke

2018-01-01

Energetic particles enter the polar atmosphere and enhance the production of nitrogen oxides and hydrogen oxides in the winter stratosphere and mesosphere. Both components are powerful ozone destroyers. Recently, it has been inferred from observations that the direct effect of energetic particle precipitation (EPP) causes significant long-term mesospheric ozone variability. Satellites observe a decrease in mesospheric ozone up to 34 % between EPP maximum and EPP minimum. Stratospheric ozone decreases due to the indirect effect of EPP by about 10-15 % observed by satellite instruments. Here, we analyze the climate impact of winter boreal idealized polar mesospheric and polar stratospheric ozone losses as caused by EPP in the coupled Max Planck Institute Earth System Model (MPI-ESM). Using radiative transfer modeling, we find that the radiative forcing of mesospheric ozone loss during polar night is small. Hence, climate effects of mesospheric ozone loss due to energetic particles seem unlikely. Stratospheric ozone loss due to energetic particles warms the winter polar stratosphere and subsequently weakens the polar vortex. However, those changes are small, and few statistically significant changes in surface climate are found.

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B.

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flowmore » rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.« less

Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

NASA Astrophysics Data System (ADS)

Prasetyaningrum, A.; Ratnawati, Jos, B.

2015-12-01

Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

The effect of ozone on the yellowing process of magnesium-deficient clonal Norway spruce grown under defined conditions.

PubMed

Siefermann-Harms, Dorothea; Payer, Hans Dieter; Schramel, Peter; Lütz, Cornelius

2005-02-01

During two vegetation periods, young clonal spruce trees (Picea abies (L.) Karst.) with sufficient and poor magnesium (Mg) supply were exposed in the environmental chambers of the GSF phytotron to three levels of ozone (daily means: 18-22, 88-130, and 135-190 microg m(-3); 10% reduction at night). Previous year's needles were examined at 4-week intervals with respect to their contents of Mg, Ca, K, Mn, N, P, and chlorophyll (Chl), various parameters of Chl fluorescence, and the stability of the isolated light-harvesting Chl-a/b-protein complex LHC II. The needles of the two nutrition variants contained more than 0.53 or less than 0.27mg Mg g(-1) needle dry matter, respectively. The ratio of variable to maximal Chl-a fluorescence of the dark-adapted needles, Fv/Fm, and the photoinhibitory quenching of Fv after light treatment, SVi.v, were affected by the Mg content of the needles rather than the ozone levels. Changes of the Chl content and the behavior of the LHC II allowed differentiating between a slow process of needle yellowing occurring under Mg deficiency only, and a rapid process of needle yellowing occurring under the combined action of Mg deficiency and ozone pollution. Only the rapid yellowing process was accompanied by destabilization of the LHC II, and the degree of destabilization was correlated with the ozone concentration present in the days before sampling. The results are consistent with observations obtained at a research site in the Central Black Forest (J Plant Physiol 161 (2004) 423).

Interannual Variability and Trends of Extratropical Ozone. Part 1; Northern Hemisphere

NASA Technical Reports Server (NTRS)

Yung, Yuk L.

2008-01-01

The authors apply principal component analysis (PCA) to the extratropical total column ozone from the combined merged ozone data product and the European Centre for Medium-Range Weather Forecasts assimilated ozone from January 1979 to August 2002. The interannual variability (IAV) of extratropical O-3 in the Northern Hemisphere (NH) is characterized by four main modes. Attributable to dominant dynamical effects, these four modes account for nearly 60% of the total ozone variance in the NH. The patterns of variability are distinctly different from those derived for total O-3 in the tropics. To relate the derived patterns of O-3 to atmospheric dynamics, similar decompositions are performed for the 30 100-Wa geopotential thickness. The results reveal intimate connections between the IAV of total ozone and the atmospheric circulation. The first two leading modes are nearly zonally symmetric and represent the connections to the annular modes and the quasi-biennial oscillation. The other two modes exhibit in-quadrature, wavenumber-1 structures that, when combined, describe the displacement of the polar vortices in response to planetary waves. In the NH, the extrema of these combined modes have preferred locations that suggest fixed topographical and land-sea thermal forcing of the involved planetary waves. Similar spatial patterns and trends in extratropical column ozone are simulated by the Goddard Earth Observation System chemistryclimate model (GEOS-CCM). The decreasing O-3 trend is captured in the first mode. The largest trend occurs at the North Pole, with values similar to-1 Dobson Unit (DU) yr(-1). There is almost no trend in tropical O-3. The trends derived from PCA are confirmed using a completely independent method, empirical mode decomposition, for zonally averaged O-3 data. The O-3 trend is also captured by mode 1 in the GEOS-CCM, but the decrease is substantially larger than that in the real atmosphere.

A New SATIRE-S Spectral Solar Irradiance Reconstruction for Solar Cycles 21-23 and Its Implications for Stratospheric Ozone*

NASA Astrophysics Data System (ADS)

Ball, William T.; Krivova, Natalie A.; Unruh, Yvonne C.; Haigh, Joanna D.; Solanki, Sami K.

2014-11-01

We present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the SATIRE-S model. The SSI reconstruction covers wavelengths between 115 and 160,000 nm and all dates between August 1974 and October 2009. This represents the first full-wavelength SATIRE-S reconstruction to cover the last three solar cycles without data gaps and with an uncertainty estimate. SATIRE-S is compared with the NRLSSI model and SORCE/SOLSTICE ultraviolet (UV) observations. SATIRE-S displays similar cycle behaviour to NRLSSI for wavelengths below 242 nm and almost twice the variability between 242 and 310 nm. During the decline of last solar cycle, between 2003 and 2008, SSI from SORCE/SOLSTICE version 12 and 10 typically displays more than three times the variability of SATIRE-S between 200 and 300 nm. All three datasets are used to model changes in stratospheric ozone within a 2D atmospheric model for a decline from high solar activity to solar minimum. The different flux changes result in different modelled ozone trends. Using NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and SORCE/SOLSTICE result in an increase. Recent publications have highlighted increases in mesospheric ozone when considering version 10 SORCE/SOLSTICE irradiances. The recalibrated SORCE/SOLSTICE version 12 irradiances result in a much smaller mesospheric ozone response than when using version 10 and now similar in magnitude to SATIRE-S. This shows that current knowledge of variations in spectral irradiance is not sufficient to warrant robust conclusions concerning the impact of solar variability on the atmosphere and climate.

Interpreting SBUV Smoothing Errors: an Example Using the Quasi-biennial Oscillation

NASA Technical Reports Server (NTRS)

Kramarova, N. A.; Bhartia, Pawan K.; Frith, S. M.; McPeters, R. D.; Stolarski, R. S.

2013-01-01

The Solar Backscattered Ultraviolet (SBUV) observing system consists of a series of instruments that have been measuring both total ozone and the ozone profile since 1970. SBUV measures the profile in the upper stratosphere with a resolution that is adequate to resolve most of the important features of that region. In the lower stratosphere the limited vertical resolution of the SBUV system means that there are components of the profile variability that SBUV cannot measure. The smoothing error, as defined in the optimal estimation retrieval method, describes the components of the profile variability that the SBUV observing system cannot measure. In this paper we provide a simple visual interpretation of the SBUV smoothing error by comparing SBUV ozone anomalies in the lower tropical stratosphere associated with the quasi-biennial oscillation (QBO) to anomalies obtained from the Aura Microwave Limb Sounder (MLS). We describe a methodology for estimating the SBUV smoothing error for monthly zonal mean (mzm) profiles. We construct covariance matrices that describe the statistics of the inter-annual ozone variability using a 6 yr record of Aura MLS and ozonesonde data. We find that the smoothing error is of the order of 1percent between 10 and 1 hPa, increasing up to 15-20 percent in the troposphere and up to 5 percent in the mesosphere. The smoothing error for total ozone columns is small, mostly less than 0.5 percent. We demonstrate that by merging the partial ozone columns from several layers in the lower stratosphere/troposphere into one thick layer, we can minimize the smoothing error. We recommend using the following layer combinations to reduce the smoothing error to about 1 percent: surface to 25 hPa (16 hPa) outside (inside) of the narrow equatorial zone 20 S-20 N.

Impact of Stratospheric Ozone Zonal Asymmetries on the Tropospheric Circulation

NASA Technical Reports Server (NTRS)

Tweedy, Olga; Waugh, Darryn; Li, Feng; Oman, Luke

2015-01-01

The depletion and recovery of Antarctic ozone plays a major role in changes of Southern Hemisphere (SH) tropospheric climate. Recent studies indicate that the lack of polar ozone asymmetries in chemistry climate models (CCM) leads to a weaker and warmer Antarctic vortex, and smaller trends in the tropospheric mid-latitude jet and the surface pressure. However, the tropospheric response to ozone asymmetries is not well understood. In this study we report on a series of integrations of the Goddard Earth Observing System Chemistry Climate Model (GEOS CCM) to further examine the effect of zonal asymmetries on the state of the stratosphere and troposphere. Integrations with the full, interactive stratospheric chemistry are compared against identical simulations using the same CCM except that (1) the monthly mean zonal mean stratospheric ozone from first simulation is prescribed and (2) ozone is relaxed to the monthly mean zonal mean ozone on a three day time scale. To analyze the tropospheric response to ozone asymmetries, we examine trends and quantify the differences in temperatures, zonal wind and surface pressure among the integrations.

A study of interferences in ozone UV and chemiluminescence monitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hudgens, E.E.; Kleindienst, T.E.; McElroy, F.F.

A study was conducted to examine interferences and other measurement anomalies in chemiluminescence and ultraviolet ozone monitors. Previous results had show that there was a positive deviation in the chemiluminescence monitors and no direct interference with ultraviolet monitors due to the presence of water at non-condensing concentrations. The present study continues this effort, examining both potential positive and negative effects of moisture and other interferences on these monitors. Aromatic compounds and their oxidation products could potentially show a positive interference with ultraviolet monitors, and test measurements were made with aromatics such as toluene, benzaldehyde, and nitrotoluene to determine their possiblemore » retention in the ozone scrubber and their absorption in the cell as a function of the humidity. A detailed examination of the scrubbers used in ultraviolet ozone monitors has also been undertaken. Ozone scrubbers that have shown anomalous behavior in the field have been studied in various reduced-efficacy modes under controlled laboratory conditions. Longer term tests of unused scrubbers for possible ozone breakthrough under exposure to various simulated field conditions were initiated.« less

Long-term changes in ozone mini-hole event frequency over the Northern Hemisphere derived from ground-based measurements

NASA Astrophysics Data System (ADS)

Krzycin, Janusz W.

2002-10-01

Decadal changes of ozone mini-hole event appearance over the Northern Hemisphere midlatitudes are examined based on daily total ozone data from seven stations having long records (four decades or more) of ozone observations. The various threshold methods for accepting and rejecting the ozone minima as mini-holes are examined. Mini-hole event activity is seen to be rather stable when averaged over a decadal time scale if the mini-holes are selected as large negative departures (exceeding 20%) relative to the moving long-term total ozone reference. The results are compared with a previous ozone mini-hole climatology derived from satellite data (TOMS measurements on board the Nimbus-7 satellite for the period 1978-93). A nonlinear statistical model (MARS), which takes into account various total ozone dynamical proxies (from NCEP-NCAR reanalysis), is used to study dynamical factors responsible for the ozone extremes over Arosa in the period 1950-99. The model explains as much as 95% of the total variance of the ozone extremes. The model-observation differences averaged over the decadal intervals are rather smooth throughout the whole period analysed. It is suggested that the short-term dynamical processes controlling the appearance of ozone extremes influenced the ozone field in a similar way before and after the onset of abrupt ozone depletion in the early 1980s. The analysis of the ozone profile and the tropopause pressure (from the ozonesondings over Hohenpeissenberg, 1966-99) during mini-hole events shows 60% ozone reduction in the lower stratosphere and an approximately 50 hPa upward shift of the thermal tropopause there.

Time series analysis of ozone data in Isfahan

NASA Astrophysics Data System (ADS)

Omidvari, M.; Hassanzadeh, S.; Hosseinibalam, F.

2008-07-01

Time series analysis used to investigate the stratospheric ozone formation and decomposition processes. Different time series methods are applied to detect the reason for extreme high ozone concentrations for each season. Data was convert into seasonal component and frequency domain, the latter has been evaluated by using the Fast Fourier Transform (FFT), spectral analysis. The power density spectrum estimated from the ozone data showed peaks at cycle duration of 22, 20, 36, 186, 365 and 40 days. According to seasonal component analysis most fluctuation was in 1999 and 2000, but the least fluctuation was in 2003. The best correlation between ozone and sun radiation was found in 2000. Other variables which are not available cause to this fluctuation in the 1999 and 2001. The trend of ozone is increasing in 1999 and is decreasing in other years.

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. Influence of temperature and humidity on ozone-surface reactivity was not strong.

Is the residual vertical velocity a good proxy for stratosphere-troposphere exchange of ozone?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Juno; Prather, Michael J.

Stratosphere-troposphere exchange (STE) of ozone (O 3) is key in the budget of tropospheric O 3, in turn affecting climate forcing and global air quality. We compare three commonly used diagnostics meant to quantify cross-tropopause O 3 fluxes with a Chemistry-Transport Model driven by two distinct European Centre forecast fields. Here, our reference case calculates accurate, geographically resolved net transport across an isosurface in artificial tracer e90 representing the tropopause. Hemispheric fluxes derived from the ozone mass budget of the lowermost stratosphere yield similar results. Use of the Brewer-Dobson residual vertical velocity as a scaled proxy for ozone flux, however,more » fails to capture the interannual variability. Thus, the common notion that the strength of stratospheric overturning circulation is a good measure for global STE does not apply to O 3. Finally, climatic variability in the modeled O 3 flux needs to be diagnosed directly rather than indirectly through the overturning circulation.« less

Is the residual vertical velocity a good proxy for stratosphere-troposphere exchange of ozone?

DOE PAGES

Hsu, Juno; Prather, Michael J.

2014-12-20

Stratosphere-troposphere exchange (STE) of ozone (O 3) is key in the budget of tropospheric O 3, in turn affecting climate forcing and global air quality. We compare three commonly used diagnostics meant to quantify cross-tropopause O 3 fluxes with a Chemistry-Transport Model driven by two distinct European Centre forecast fields. Here, our reference case calculates accurate, geographically resolved net transport across an isosurface in artificial tracer e90 representing the tropopause. Hemispheric fluxes derived from the ozone mass budget of the lowermost stratosphere yield similar results. Use of the Brewer-Dobson residual vertical velocity as a scaled proxy for ozone flux, however,more » fails to capture the interannual variability. Thus, the common notion that the strength of stratospheric overturning circulation is a good measure for global STE does not apply to O 3. Finally, climatic variability in the modeled O 3 flux needs to be diagnosed directly rather than indirectly through the overturning circulation.« less

Influence of climate variability on near-surface ozone depletion events in the Arctic spring

NASA Astrophysics Data System (ADS)

Koo, Ja-Ho; Wang, Yuhang; Jiang, Tianyu; Deng, Yi; Oltmans, Samuel J.; Solberg, Sverre

2014-04-01

Near-surface ozone depletion events (ODEs) generally occur in the Arctic spring, and the frequency shows large interannual variations. We use surface ozone measurements at Barrow, Alert, and Zeppelinfjellet to analyze if their variations are due to climate variability. In years with frequent ODEs at Barrow and Alert, the western Pacific (WP) teleconnection pattern is usually in its negative phase, during which the Pacific jet is strengthened but the storm track originated over the western Pacific is weakened. Both factors tend to reduce the transport of ozone-rich air mass from midlatitudes to the Arctic, creating a favorable environment for the ODEs. The correlation of ODE frequencies at Zeppelinfjellet with WP indices is higher in the 2000s, reflecting stronger influence of the WP pattern in recent decade to cover ODEs in broader Arctic regions. We find that the WP pattern can be used to diagnose ODE changes and subsequent environmental impacts in the Arctic spring.

The role of plant phenology in stomatal ozone flux modeling.

PubMed

Anav, Alessandro; Liu, Qiang; De Marco, Alessandra; Proietti, Chiara; Savi, Flavia; Paoletti, Elena; Piao, Shilong

2018-01-01

Plant phenology plays a pivotal role in the climate system as it regulates the gas exchange between the biosphere and the atmosphere. The uptake of ozone by forest is estimated through several meteorological variables and a specific function describing the beginning and the termination of plant growing season; actually, in many risk assessment studies, this function is based on a simple latitude and topography model. In this study, using two satellite datasets, we apply and compare six methods to estimate the start and the end dates of the growing season across a large region covering all Europe for the year 2011. Results show a large variability between the green-up and dormancy dates estimated using the six different methods, with differences greater than one month. However, interestingly, all the methods display a common spatial pattern in the uptake of ozone by forests with a marked change in the magnitude, up to 1.9 TgO 3 /year, and corresponding to a difference of 25% in the amount of ozone that enters the leaves. Our results indicate that improved estimates of ozone fluxes require a better representation of plant phenology in the models used for O 3 risk assessment. © 2017 John Wiley & Sons Ltd.

Analysis of the breakdown of the Antarctic circumpolar vortex using TOMS ozone data

NASA Technical Reports Server (NTRS)

Bowman, Kenneth P.

1987-01-01

Climatological analysis of data from the Total Ozone Mapping Spectrometer (TOMS) on the Nimbus 7 satellite has shown that the annual cycles of ozone are very different in the Arctic and Antarctic. The annual cycle in the Arctic is a relatively smooth annual sine wave; but in the Antarctic the circumpolar vortex breaks down rapidly during the Southern Hemisphere spring (September through November), producing a rapid rise in total ozone and a sawtooth-shaped annual cycle. The evolution of the Antarctic total ozone field during the vortex breakdown was studied by computing areally-integrated ozone amounts from the TOMS data. This technique avoids substantial difficulties with using zonally-averaged ozone amounts to study the asymmetric breakdown phenomenon. Variability of total ozone is found to be large both within an individual year and between different years. During the last decade monthly-mean total ozone values in the Antarctic during the springtime vortex breakdown period have decreased dramatically. The ozone-area statistics indicate that the decrease has resulted in part from changes in the timing of the vortex breakdown and resultant ozone increase, which have occurred later during recent years. Analysis of the spatial scales involved in the ozone transport and mixing that occur during the vortex breakdown is now underway. Reliable calculation of diagnostic quantities like areally-integrated ozone is possible only with the high-resolution, two-dimensional, daily coverage provided by the TOMS instrument.

Surface ozone variability at Kislovodsk Observatory

NASA Technical Reports Server (NTRS)

Elansky, Nikolay F.; Makarov, Oleg V.; Senik, Irina A.

1994-01-01

The results of the surface ozone observations at the Observatory 'Kislovodsk', situated in the North Caucasus at the altitude 2070 m a.s.l., are given. The observatory is in the background conditions and the variations of the surface ozone are determined by the natural dynamic and photochemical processes. The mean value of the concentration and its seasonal variations are very near to those obtained at the high-mountain stations in Alps. The daily variations have the features, which remain stable during all warm period of the year (April-October). These features, including the minimum of the surface ozone at noon, are formed by the mountain-valley circulation. The significant variations of the surface ozone are connected with the unstationary lee waves.

Derivation of Tropospheric Column Ozone from the EPTOMS/GOES Co-Located Data Sets using the Cloud Slicing Technique

NASA Technical Reports Server (NTRS)

Ahn, C.; Ziemke, J. R.; Chandra, S.; Bhartia, P. K.

2002-01-01

A recently developed technique called cloud slicing used for deriving upper tropospheric ozone from the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) instrument combined together with temperature-humidity and infrared radiometer (THIR) is no longer applicable to the Earth Probe TOMS (EPTOMS) because EPTOMS does not have an instrument to measure cloud top temperatures. For continuing monitoring of tropospheric ozone between 200-500hPa and testing the feasibility of this technique across spacecrafts, EPTOMS data are co-located in time and space with the Geostationary Operational Environmental Satellite (GOES)-8 infrared data for 2001 and early 2002, covering most of North and South America (45S-45N and 120W-30W). The maximum column amounts for the mid-latitudinal sites of the northern hemisphere are found in the March-May season. For the mid-latitudinal sites of the southern hemisphere, the highest column amounts are found in the September-November season, although overall seasonal variability is smaller than those of the northern hemisphere. The tropical sites show the weakest seasonal variability compared to higher latitudes. The derived results for selected sites are cross validated qualitatively with the seasonality of ozonesonde observations and the results from THIR analyses over the 1979-1984 time period due to the lack of available ozonesonde measurements to study sites for 2001. These comparisons show a reasonably good agreement among THIR, ozonesonde observations, and cloud slicing-derived column ozone. With very limited co-located EPTOMS/GOES data sets, the cloud slicing technique is still viable to derive the upper tropospheric column ozone. Two new variant approaches, High-Low (HL) cloud slicing and ozone profile derivation from cloud slicing are introduced to estimate column ozone amounts using the entire cloud information in the troposphere.

A New Technique for Retrieval of Tropospheric and Stratospheric Ozone Profiles using Sky Radiance Measurements at Multiple View Angles: Application to a Brewer Spectrometer

NASA Technical Reports Server (NTRS)

Tzortziou, Maria; Krotkov, Nickolay A.; Cede, Alexander; Herman, Jay R.; Vasilkov, Alexander

2008-01-01

This paper describes and applies a new technique for retrieving diurnal variability in tropospheric ozone vertical distribution using ground-based measurements of ultraviolet sky radiances. The measured radiances are obtained by a polarization-insensitive modified Brewer double spectrometer located at Goddard Space Flight Center, in Greenbelt, Maryland, USA. Results demonstrate that the Brewer angular (0-72deg viewing zenith angle) and spectral (303-320 nm) measurements of sky radiance in the solar principal plane provide sufficient information to derive tropospheric ozone diurnal variability. In addition, the Brewer measurements provide stratospheric ozone vertical distributions at least twice per day near sunrise and sunset. Frequent measurements of total column ozone amounts from direct-sun observations are used as constraints in the retrieval. The vertical ozone profile resolution is shown in terms of averaging kernels to yield at least four points in the troposphere-low stratosphere, including good information in Umkehr layer 0 (0-5 km). The focus of this paper is on the derivation of stratospheric and tropospheric ozone profiles using both simulated and measured radiances. We briefly discuss the necessary modifications of the Brewer spectrometer that were used to eliminate instrumental polarization sensitivity so that accurate sky radiances can be obtained in the presence of strong Rayleigh scattering and aerosols. The results demonstrate that including a site-specific and time-dependent aerosol correction, based on Brewer direct-sun observations of aerosol optical thickness, is critical to minimize the sky radiance residuals as a function of observing angle in the optimal estimation inversion algorithm and improve the accuracy of the retrieved ozone profile.

Children's and Adults' Knowledge and Models of Reasoning about the Ozone Layer and Its Depletion.

ERIC Educational Resources Information Center

Leighton, Jacqueline P.; Bisanz, Gay L.

2003-01-01

Examines children's and adults' knowledge of the ozone layer and its depletion, whether this knowledge increases with age, and how the ozone layer and ozone hole might be structured as scientific concepts. Uses a standardized set of questions to interview children and adults in Canada. Discusses implications of the results for health…

Modeling and Prediction of Monthly Total Ozone Concentrations by Use of an Artificial Neural Network Based on Principal Component Analysis

NASA Astrophysics Data System (ADS)

Chattopadhyay, Surajit; Chattopadhyay, Goutami

2012-10-01

In the work discussed in this paper we considered total ozone time series over Kolkata (22°34'10.92″N, 88°22'10.92″E), an urban area in eastern India. Using cloud cover, average temperature, and rainfall as the predictors, we developed an artificial neural network, in the form of a multilayer perceptron with sigmoid non-linearity, for prediction of monthly total ozone concentrations from values of the predictors in previous months. We also estimated total ozone from values of the predictors in the same month. Before development of the neural network model we removed multicollinearity by means of principal component analysis. On the basis of the variables extracted by principal component analysis, we developed three artificial neural network models. By rigorous statistical assessment it was found that cloud cover and rainfall can act as good predictors for monthly total ozone when they are considered as the set of input variables for the neural network model constructed in the form of a multilayer perceptron. In general, the artificial neural network has good potential for predicting and estimating monthly total ozone on the basis of the meteorological predictors. It was further observed that during pre-monsoon and winter seasons, the proposed models perform better than during and after the monsoon.

A climatology of visible surface reflectance spectra

NASA Astrophysics Data System (ADS)

Zoogman, Peter; Liu, Xiong; Chance, Kelly; Sun, Qingsong; Schaaf, Crystal; Mahr, Tobias; Wagner, Thomas

2016-09-01

We present a high spectral resolution climatology of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone and other atmospheric species. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is planned to measure backscattered solar radiation in the 290-740 nm range, including the ultraviolet and visible Chappuis ozone bands. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a high spectral resolution, comparable to that of TEMPO (0.6 nm). Using the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirection Reflectance Distribution Function (BRDF)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. The Global Ozone Monitoring Experiment-2 (GOME-2) Lambertian Equivalent Reflectance (LER) product provides complementary information over water and snow scenes. Preliminary results using this approach in multispectral ultraviolet+visible ozone retrievals from the GOME-2 instrument show significant improvement to the fitting residuals over vegetated scenes.

Investigation of isotope effects of ozone as a function of temperature

NASA Astrophysics Data System (ADS)

McMahon, Daniel J.

Ozone is an important oxidizer in the atmosphere and plays a crucial role as a cleanser, removing various compounds such NOx and SOx. It also is intriguing to those that study stable isotopes as it has a unique signature found in no other oxygen containing molecule. Ozone is observed to fractionate mass independently, which means it does not follow the typical delta 17O /delta18O = 0.52 ratio expected for molecules enriched with 17O and 18O. The magnitude of ozone's mass independent enrichment has been studied in laboratory experiments and atmospheric observations but its explanation is still incomplete. Symmetry of the isotopically substituted ozone is postulated to be the source of mass independent enrichment and this thesis will build on that explanation to examine the magnitude of isotopic enrichment as a function of temperature. Understanding of the kinetics of ozone formation has come a long way from early predictions of enrichments >200‰ However, while our ability to accurately model ozone's bulk isotopic enrichment has improved to include separate rates for the formation of asymmetric and symmetric ozone, rate experiments are sparse for 17O and of low precision. To improve our understanding of ozone's enrichment, this study presents a temperature dependent enrichment experiment and series of models to predict asymmetric mass independent fractionation. This also served to examine ozone's enrichment in the troposphere by using an open flow experimental setup which is in contrast to previous works examining ozone enrichment in a closed system. Our experimental observations show that under tropospheric conditions, ozone should have delta17O ≈ 75‰, delta18O ≈ 80‰, and delta 17O ≈ 33‰. The models were able to match experimental values, often within 1‰, and with minimal assumptions, predict asymmetric ozone to have delta17O=47.5‰. This value is important as ozone transfers its terminal atom to species it oxidizes and will be the starting point to using ozone as a tracer in atmospheric reactions. Modeling improves our understanding of ozone's enrichments but these predictions must be validated by atmospheric observations. Previous tropospheric ozone sampling studies produced data of low precision but still showed relatively good agreement with our laboratory observations. In order to obtain better isotopic data a proxy method for sampling ozone's terminal atom is needed. Reaction with nitrite in solution is promising as the reaction is rapid and efficient. However we were unable to obtain tropospheric ozone observations as nitrite processing methods could not be perfected to remove nitrate blank concentrations. We do present the merits of using nitrite to react with atmospheric ozone and the suggest purification steps that may allow this method to be successful in the future.

Intermittent noise stress causes baroreflex desensitization and decreased heart rate variability in Wistar Kyoto rats exposed to ozone

EPA Science Inventory

This study shows that intermittent noise stress worsens the cardiopulmonary response of rats to ozone. It increases electrical disturbances and causes dysfunction the homeostatic regulation of the heart and vasculature. Although the acute cardiovascular health impacts o...

Ozone exposure and stomatal sluggishness in different plant physiognomic classes

Treesearch

E. Paoletti; N.E. Grulke

2010-01-01

Gas exchange responses to static and variable light were tested in three species: snap bean (Phaseolus vulgaris, two cultivars), California black oak (Quercus kelloggii), and blue oak (Q. douglasii). The effects of 1-month (snap beans) and 2-month (oaks) O3 (ozone) exposure (70&...

The Total Ozone Series of Arosa: History, Homogenization and new results using statistical extreme value theory

NASA Astrophysics Data System (ADS)

Staehelin, J.; Rieder, H. E.; Maeder, J. A.; Ribatet, M.; Davison, A. C.; Stübi, R.

2009-04-01

Atmospheric ozone protects the biota living at the Earth's surface from harmful solar UV-B and UV-C radiation. The global ozone shield is expected to gradually recover from the anthropogenic disturbance of ozone depleting substances (ODS) in the coming decades. The stratospheric ozone layer at extratropics might significantly increase above the thickness of the chemically undisturbed atmosphere which might enhance ozone concentrations at the tropopause altitude where ozone is an important greenhouse gas. At Arosa, a resort village in the Swiss Alps, total ozone measurements started in 1926 leading to the longest total ozone series of the world. One Fery spectrograph and seven Dobson spectrophotometers were operated at Arosa and the method used to homogenize the series will be presented. Due to its unique length the series allows studying total ozone in the chemically undisturbed as well as in the ODS loaded stratosphere. The series is particularly valuable to study natural variability in the period prior to 1970, when ODS started to affect stratospheric ozone. Concepts developed by extreme value statistics allow objective definitions of "ozone extreme high" and "ozone extreme low" values by fitting the (daily mean) time series using the Generalized Pareto Distribution (GPD). Extreme high ozone events can be attributed to effects of ElNino and/or NAO, whereas in the chemically disturbed stratosphere high frequencies of extreme low total ozone values simultaneously occur with periods of strong polar ozone depletion (identified by statistical modeling with Equivalent Stratospheric Chlorine times Volume of Stratospheric Polar Clouds) and volcanic eruptions (such as El Chichon and Pinatubo).

Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abu Amr, Salem S.; Aziz, Hamidi Abdul, E-mail: cehamidi@eng.usm.my; Adlan, Mohd Nordin

Highlights: ► Ozone and persulfate reagent (O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) was used to treat stabilized leachate. ► Central composite design (CCD) with response surface methodology (RSM) was applied. ► Operating variables including ozone and persulfate dosage, pH variance, and reaction time. ► Optimum removal of COD, color, and NH{sub 3}–N was 72%, 96%, and 76%, respectively. ► A good value of ozone consumption (OC) obtained with 0.60 (kg O{sub 3}/kg COD). - Abstract: The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate inmore » an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH{sub 3}–N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m{sup 3} ozone, 1 g/1 g COD{sub 0}/S{sub 2}O{sub 8}{sup 2-} ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH{sub 3}–N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O{sub 3}/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S{sub 2}O{sub 8}{sup 2-} only, to evaluate its effectiveness. The combined method (i.e., O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) achieved higher removal efficiencies for COD, color, and NH{sub 3}–N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate.« less

Long term changes of tropospheric Nitrogen Dioxide over Pakistan derived from Ozone Monitoring Instrument (OMI) during the time period of October 2004 to December 2014

NASA Astrophysics Data System (ADS)

Murtaza, Rabbia; Fahim Khokhar, Muhammad

2016-07-01

Urban air pollution is causing huge number of diseases and deaths annually. Nitrogen dioxide is an important component of urban air pollution and a precursor to particulate matter, ground level ozone, and acid rain. The satellite based measurements of nitrogen dioxide from Ozone Monitoring Instrument (OMI) can help in analyzing spatio temporal variability in ground level concentrations within a large urban area. In this study, the spatial and temporal distributions of tropospheric nitrogen dioxide Vertical Column Densities (VCDs) over Pakistan are presented from 2004 to 2014. The results showed that the winter season is having high nitrogen dioxide levels as compared to summers. The increase can be attributed to the anthropogenic activities especially thermal power generation and traffic count. Punjab is one of the major provinces with high nitrogen dioxide levels followed by Sindh, Khyber Pakhtunkhwa and Balochistan. Six hotspots have been examined in the present study such as Lahore, Islamabad, Karachi, Faisalabad, Okara and Multan. Emissions of nitrogen compounds from thermal power plants and transportation sector represent a significant fraction of the total nitrogen dioxide emissions to the atmosphere.

Ozone killing action against bacterial and fungal species; microbiological testing of a domestic ozone generator.

PubMed

Dyas, A; Boughton, B J; Das, B C

1983-10-01

The action of ozone generated from a small domestic device was examined with a view to using it in clinical isolation units accommodating immunosuppressed patients. Over a six-hour period in an average size room the device did not generate sufficient ozone to suppress bacterial and fungal growth. A useful bactericidal action, against a variety of human pathogens was achieved with ozone concentrations between 0.3 to 0.9 ppm. Bactericidal ozone concentrations are close to the limit permitted for human exposure however and further experiments are indicated.

Demonstration of long-term increases in tropospheric O3 levels: causes and potential impacts.

PubMed

Susaya, Janice; Kim, Ki-Hyun; Shon, Zang-Ho; Brown, Richard J C

2013-09-01

Ground-level ozone (O3) is a well-known atmospheric pollutant with its adverse impacts on the environment and human health. Here, the tropospheric O3 concentrations monitored in seven major cities in Korea at monthly intervals over a 22-year period (1989-2010) are presented, and their long-term variability examined. The analysis of annual mean values of O3 (in nmolmol(-1), or ppb) showed a noticeable increase of 118±69% in all seven cities over the two decades (p<0.01). Changes in O3 levels are closely associated with both environmental (e.g., NOx (NO+NO2), SO2, CO, and total suspended particles (TSPs) (p<0.01), temperature, and sunshine hours) and common anthropogenic variables (e.g., population density and number of vehicles). Evidence collected in this study suggests that the atmospheric conditions in most major cities of Korea should be volatile organic compounds (VOCs) sensitive or NOx saturated with respect to O3 formation. As such, establishment of a proper management strategy seems a sensible approach to control tropospheric ozone concentrations in densely populated cities. Copyright © 2013 Elsevier Ltd. All rights reserved.

DOAS-based total column ozone retrieval from Phaethon system

NASA Astrophysics Data System (ADS)

Gkertsi, F.; Bais, A. F.; Kouremeti, N.; Drosoglou, Th; Fountoulakis, I.; Fragkos, K.

2018-05-01

This study introduces the measurement of the total ozone column using Differential Optical Absorption Spectroscopy (DOAS) analysis of direct-sun spectra recorded by the Phaethon system. This methodology is based on the analysis of spectra relative to a reference spectrum that has been recorded by the same instrument. The slant column density of ozone associated with the reference spectrum is derived by Langley extrapolation. Total ozone data derived by Phaethon over two years in Thessaloniki are compared with those of a collocated, well-maintained and calibrated, Brewer spectrophotometer. When the retrieval of total ozone is based on the absorption cross sections of (Paur and Bass, 1984) at 228 K, Phaethon shows an average overestimation of 1.85 ± 1.86%. Taking into account the effect of the day-to-day variability of stratospheric temperature on total ozone derived by both systems, the bias is reduced to 0.94 ± 1.26%. The sensitivity of the total ozone retrieval to changes in temperature is larger for Phaethon than for Brewer.

On the role of ozone feedback in the ENSO amplitude response under global warming.

PubMed

Nowack, Peer J; Braesicke, Peter; Luke Abraham, N; Pyle, John A

2017-04-28

The El Niño-Southern Oscillation (ENSO) in the tropical Pacific Ocean is of key importance to global climate and weather. However, state-of-the-art climate models still disagree on the ENSO's response under climate change. The potential role of atmospheric ozone changes in this context has not been explored before. Here we show that differences between typical model representations of ozone can have a first-order impact on ENSO amplitude projections in climate sensitivity simulations. The vertical temperature gradient of the tropical middle-to-upper troposphere adjusts to ozone changes in the upper troposphere and lower stratosphere, modifying the Walker circulation and consequently tropical Pacific surface temperature gradients. We show that neglecting ozone changes thus results in a significant increase in the number of extreme ENSO events in our model. Climate modeling studies of the ENSO often neglect changes in ozone. We therefore highlight the need to understand better the coupling between ozone, the tropospheric circulation, and climate variability.

Influence of the North American monsoon on Southern California tropospheric ozone levels during summer in 2013 and 2014

NASA Astrophysics Data System (ADS)

Granados-Muñoz, Maria Jose; Johnson, Matthew S.; Leblanc, Thierry

2017-06-01

The impact of the North American (NA) monsoon on tropospheric ozone variability in Southern California is investigated using lidar measurements at Jet Propulsion Laboratory-Table Mountain Facility, California, and the chemical-transport model GEOS-Chem. Routine lidar observations obtained in July-August 2013-2014 reveal a consistent ozone enhancement of 23 ppbv in the free troposphere (6-9 km), when ozone-rich air is transported along the western edge of the upper level anticyclone associated with the NA monsoon from regions where maximum lightning-induced NOx production occurs. When the high-pressure system shifts to the southeast, a zonal westerly flow of the air parcels reaching the Table Mountain Facility (TMF) occurs, prohibiting the lightning-induced ozone enhanced air to reach TMF. This modulation of tropospheric ozone by the position of the NA monsoon anticyclone could have implications on long-term ozone trends associated with our changing climate, due to the expected widening of the tropical belt affecting the strength and position of the anticyclone.

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.

Tropospheric Ozone Source Attribution in Southern California during Summer 2014 Based on Lidar Measurements and Model Simulations

NASA Technical Reports Server (NTRS)

Granados Munoz, Maria Jose; Johnson, Matthew S.; Leblanc, Thierry

2016-01-01

In the past decades, significant efforts have been made to increase tropospheric ozone long-term monitoring. A large number of ground-based, airborne and space-borne instruments are currently providing valuable data to contribute to better understand tropospheric ozone budget and variability. Nonetheless, most of these instruments provide in-situ surface and column-integrated data, whereas vertically resolved measurements are still scarce. Besides ozonesondes and aircraft, lidar measurements have proven to be valuable tropospheric ozone profilers. Using the measurements from the tropospheric ozone differential absorption lidar (DIAL) located at the JPL Table Mountain Facility, California, and the GEOS-Chem and GEOS-5 model outputs, the impact of the North American monsoon on tropospheric ozone during summer 2014 is investigated. The influence of the Monsoon lightning-induced NOx will be evaluated against other sources (e.g. local anthropogenic emissions and the stratosphere) using also complementary data such as backward-trajectories analysis, coincident water vapor lidar measurements, and surface ozone in-situ measurements.

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.

An analysis of the first two years of GASP data

NASA Technical Reports Server (NTRS)

Holdeman, J. D.; Nastrom, G. D.; Falconer, P. D.

1977-01-01

Distributions of mean ozone levels from the first two years of data from the NASA Global Atmospheric Sampling Program (GASP) show spatial and temporal variations in agreement with previous measurements. The standard deviations of these distributions reflect the large natural variability of ozone levels in the altitude range of the GASP measurements. Monthly mean levels of ozone below the tropopause show an annual cycle with a spring maximum which is believed to result from transport from the stratosphere. Correlations of ozone with independent meteorological parameters, and meteorological parameters obtained by the GASP systems show that this transport occurs primarily through cyclogenesis at mid-latitudes.

Natural variability of tropical upper stratospheric ozone inferred from the Atmosphere Explorer backscatter ultraviolet experiment

NASA Technical Reports Server (NTRS)

Frederick, J. E.; Abrams, R. B.; Dasgupta, R.; Guenther, B.

1981-01-01

Analysis of backscattered ultraviolet radiances observed at tropical latitudes by the Atmosphere Explorer-E satellite reveals both annual and semiannual cycles in upper stratospheric ozone. The annual variation dominates the signal at wavelengths which sense ozone primarily above 45 km while below this, to the lowest altitude sensed, 35 km, the semiannual component has comparable amplitude. Comparison of radiance measurements taken with the same instrument at solar minimum during 1976 and solar maximum in 1979 show no significant differences. This suggests that variations in upper stratospheric ozone over the solar cycle are small, although the data presently available do not allow a definite conclusion.

Optimization of Ozonation Process for the Reduction of Excess Sludge Production from Activated Sludge Process of Sago Industry Wastewater Using Central Composite Design

PubMed Central

Subha, B.; Muthukumar, M.

2012-01-01

Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R 2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction. PMID:22593666

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.

Statistical problems in measuring surface ozone and modelling its patterns

NASA Astrophysics Data System (ADS)

Hutchison, Paul Stewart

The Thesis examines ground level air pollution data supplied by ITE Bush, Penicuik, Midlothian, Scotland. There is a brief examination of sulphur dioxide concentration data, but the Thesis is primarily concerned with ozone. The diurnal behaviour of ozone is the major topic, and a new methodology of classification of 'ozone days' is introduced and discussed. In chapter 2, the inverse Gaussian distribution is considered and rejected as a possible alternative to the standard approach of using the lognormal as a model for the frequency distribution of observed sulphur dioxide concentrations. In chapter 3, the behaviour of digital gas pollution analysers is investigated by making use of data obtained from two such machines operating side by side. A time series model of the differences between the readings obtained from the two machines is considered, and possible effects on modelling discussed. In chapter 4, the changes in the diurnal behaviour of ozone over a year are examined. A new approach involving a distortion of the time axis is shown to give diurnal ozone curves more homogeneous properties and have beneficial effects for modelling purposes. Chapter 5 extends the analysis of the diurnal behaviour of ozone begun in chapter 4 by considering individual 'ozone days' and attempting to classify them as one of several typical 'types' of day. The time distortion method introduced in chapter 4 is used, and a new classification methodology is introduced for considering data of this type. The statistical properties of this method are discussed in chapter 6.

TRPA1 mediates changes in heart rate variability and cardiac mechanical function in mice exposed to acrolein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurhanewicz, Nicole

Short-term exposure to ambient air pollution is linked with adverse cardiovascular effects. While previous research focused primarily on particulate matter-induced responses, gaseous air pollutants also contribute to cause short-term cardiovascular effects. Mechanisms underlying such effects have not been adequately described, however the immediate nature of the response suggests involvement of irritant neural activation and downstream autonomic dysfunction. Thus, this study examines the role of TRPA1, an irritant sensory receptor found in the airways, in the cardiac response of mice to acrolein and ozone. Conscious unrestrained wild-type C57BL/6 (WT) and TRPA1 knockout (KO) mice implanted with radiotelemeters were exposed once tomore » 3 ppm acrolein, 0.3 ppm ozone, or filtered air. Heart rate (HR) and electrocardiogram (ECG) were recorded continuously before, during and after exposure. Analysis of ECG morphology, incidence of arrhythmia and heart rate variability (HRV) were performed. Cardiac mechanical function was assessed using a Langendorff perfusion preparation 24 h post-exposure. Acrolein exposure increased HRV independent of HR, as well as incidence of arrhythmia. Acrolein also increased left ventricular developed pressure in WT mice at 24 h post-exposure. Ozone did not produce any changes in cardiac function. Neither gas produced ECG effects, changes in HRV, arrhythmogenesis, or mechanical function in KO mice. These data demonstrate that a single exposure to acrolein causes cardiac dysfunction through TRPA1 activation and autonomic imbalance characterized by a shift toward parasympathetic modulation. Furthermore, it is clear from the lack of ozone effects that although gaseous irritants are capable of eliciting immediate cardiac changes, gas concentration and properties play important roles. - Highlights: • Acute acrolein exposure causes autonomic imbalance and altered CV function in mice. • TRPA1 mediates acrolein-induced autonomic nervous system cardiac effects. • Sensory irritation contributes to acrolein-induced cardiac arrhythmia & dysfunction.« less

Total ozone influence on the surface UV-B radiation in the late spring-summer 1963-1997: An analysis of multiple timescales

NASA Astrophysics Data System (ADS)

KrzyśCin, Janusz W.

2000-02-01

Monthly means and minima of total ozone for the late springs and summers (May-August) of 1963-1997 have been examined for the European Dobson stations (Arosa, Belsk, Hohenpeissenberg, Hradec Kralove, Uccle). It is shown that long-term tendencies in total ozone means were almost similar to those in the total ozone minima. Analyses of the late spring/summer means of UV daily doses, total ozone, and global solar radiation (proxy for the overall atmospheric transparency), measured at Belsk (52°N, 21°E) for the period 1976-1996, show that an importance of the total ozone changes for the UV-B level increases with the timescale. Decadal variations in total ozone are the main source of the UV trend at Belsk. Frequency of appearance of extreme daily total ozone values in the selected late spring/summer season seems to be important for analyses of the ozone forcing in the interannual timescale. Regional and temporal differences in the number of days with extreme low ozone values are discussed using the total ozone extrema taken at Arosa, Belsk, and Hradec Kralove in the 1963-1997 period. A statistical model is developed for diagnosis of the next day value of the UV-B level. The changes in the overall atmospheric transparency are essential for the UV-B level when the day-to-day variations in the UV forcing factors are examined.

Inflammatory Cytokines and White Blood Cell Counts Response to Environmental Levels of Diesel Exhaust and Ozone Inhalation Exposures

EPA Science Inventory

Epidemiological observations of urban inhalation exposures to diesel exhaust (DE) and ozone (O3) have shown pre-clinical cardiopulmonary responses in humans. Identifying the key biological mechanisms that initiate these health bioindicators is difficult due to variability in envi...

Environmental effects of ozone depletion and its interactions with climate change: Progress report, 2016

EPA Science Inventory

When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously believed. As a result of this, human health and environmental issues will be longer-lasting and more regionally variable...

Children's Use of Metaphors in Relation To Their Mental Models: The Case of the Ozone Layer and Its Depletion.

ERIC Educational Resources Information Center

Christidou, Vasilia; Koulaidis, Vasilis; Christidis, Theodor

1997-01-01

Examines the relationship between children's use of metaphors and their mental models concerning the ozone layer and ozone layer depletion. Results indicate that the way children represent the role and depletion of ozone is strongly correlated with the types of metaphors they use while constructing and/or articulating their models. Also discusses…

Highlights from the 1998-2000 SHADOZ (Southern Hemisphere Additional Ozonesondes) Satellite Validation Project

NASA Technical Reports Server (NTRS)

Witte, J. C.; Thompson, A. M.; Fortuin, P.; Einsudi, Franco (Technical Monitor)

2001-01-01

There are three years of data (more than 1000 individual ozone profiles) available from a network of 10 southern hemisphere tropical and subtropical stations, designated the Southern Hemisphere ADditional OZonesondes (SHADOZ) project. Since late 1999, a tropical station in the northern hemisphere (Paramaribo, Surinam; lat/long) joined SHADOZ, providing coordinated weekly ozone and radiosonde data from the surface to approx. 7 hPa for satellite validation, process studies, and model evaluation. Profiles are also collected at: Ascension Island; Nairobi, Kenya; Irene, South Africa; R (union Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. The archive, station characteristics and photos are available at http://code9l6.gsfc.nasa.gov/Data_ services/shadoz>. SHADOZ ozone time-series and profiles in 1998-2000 display highly variable tropospheric ozone, a zonal wave-one pattern in total (and tropospheric) column ozone, and signatures of the Quasi-Biennial Oscillation (QBO) in stratospheric ozone. Total, stratospheric and tropospheric column ozone amounts peak between August and November and are lowest between March and May. Integrated total ozone column amounts from the sondes are lower than independent measurements from a ground-based network and from the TOMS (Total Ozone Mapping Spectrometer) satellite (version 7 data).

Kelvin waves in the tropical stratosphere observed in OMPS-LP ozone measurements

NASA Astrophysics Data System (ADS)

Randel, W. J.; Park, M.

2017-12-01

We investigate equatorial waves in the tropical stratosphere using OMPS limb profiler (LP) ozone measurements spanning 2012-2017. The OMPS-LP data show clear evidence of eastward propagating planetary-scale Kelvin waves with periods near 15-20 days, and these feature are strongly modulated by the background winds linked to the quasi-biennial oscillation (QBO). We study coherence between OMPS-LP ozone and GPS radio occultation temperature measurements, and use these analyses to evaluate data quality and variability in the tropical stratosphere.

Past Changes in the Vertical Distribution of Ozone Part 1: Measurement Techniques, Uncertainties and Availability

NASA Technical Reports Server (NTRS)

Hassler, B.; Petropavlovskikh, I.; Staehelin, J.; August, T.; Bhartia, P. K.; Clerbaux, C.; Degenstein, D.; Maziere, M. De; Dinelli, B. M.; Dudhia, A.;

A mid-latitude ozone model for the 1976 U.S. standard atmosphere

NASA Technical Reports Server (NTRS)

Krueger, A. J.; Minzner, R. A.

1976-01-01

A mid-latitude northern hemisphere model of the daytime ozone distribution in the troposphere, stratosphere, and lower mesosphere has been constructed. Data from rocket soundings in the latitude range of 45 deg N + or - 15 deg N, results of balloon soundings at latitudes from 41 to 47 deg N, and latitude gradients from satellite ozone observations have been combined to produce estimates of the annual mean ozone concentration and its variability at heights up to 74 km for an effective latitude of 45 deg N. This model is a revision for heights above 26 km of the tentative mid-latitude ozone model, included in the U.S. Standard Atmosphere Supplements, 1966, and has been adopted for use in the U.S. Standard Atmosphere, 1976.

Bromide's effect on DBP formation, speciation, and control; Part 1: Ozonation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukairy, H.M.; Summers, R.S.; Miltner, R.J.

1994-06-01

The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection by-products (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalomethanes (THMs), six haloacetic acids (HAAs), and total organic halide (TOX). Increasing the ozone dosage oxidized bromide to bromate, decreasing the bromide for incorporation into DBPs. Bromate concentrations were linearly correlated with ozone residuals. Changes in the bromine incorporation factors n and n[prime] reflected differences in the resulting speciation of THMs and HAAs, respectively. Because TOX measurements based on chloride equivalence maymore » underestimate the halogenated DBP yield for high-bromide waters, a procedure is described whereby bromide and bromate concentrations were used to correct the TOX measurement.« less

An analysis of the first two years of GASP data. [Global Atmospheric Sampling Program

NASA Technical Reports Server (NTRS)

Holdeman, J. D.; Nastrom, G. D.; Falconer, P. D.

1978-01-01

Distributions of mean ozone levels from the first two years of data from the NASA Global Atmospheric Sampling Program (GASP) show spatial and temporal variations in agreement with previous measurements. The standard deviations of these distributions reflect the large natural variability of ozone levels in the altitude range of the GASP measurements. Monthly mean levels of ozone below the tropopause show an annual cycle with a spring maximum which is believed to result from transport from the stratosphere. Correlations of ozone with independent meteorological parameters, and meteorological parameters obtained by the GASP systems show that this transport occurs primarily through cyclogenesis at mid-latitudes. The GASP water vapor data, analyzed with respect to the location of the tropopause, correlates well with the simultaneously obtained ozone and cloud data.

Impact of East Asian Summer Monsoon on Surface Ozone Pattern in China

NASA Astrophysics Data System (ADS)

Li, Shu; Wang, Tijian; Huang, Xing; Pu, Xi; Li, Mengmeng; Chen, Pulong; Yang, Xiu-Qun; Wang, Minghuai

2018-01-01

Tropospheric ozone plays a key role in regional and global atmospheric and climate systems. In East Asia, ozone can be affected both in concentration level and spatial pattern by typical monsoon climate. This paper uses three different indices to identify the strength of East Asian summer monsoon (EASM) and explores the possible impact of EASM intensity on the ozone pattern through synthetic and process analysis. The difference in ozone between three strong and three weak monsoon years was analyzed using the simulations from regional climate model RegCM4-Chem. It was found that EASM intensity can significantly influence the spatial distribution of ozone in the lower troposphere. When EASM is strong, ozone in the eastern part of China (28°N - 42° N) is reduced, but the inverse is detected in the north and south. The surface ozone difference ranges from -7 to 7 ppbv during the 3 months (June to August) of the EASM, with the most obvious difference in August. Difference of the 3 months' average ozone ranges from -3.5 to 4 ppbv. Process analysis shows that the uppermost factor controlling ozone level during summer monsoon seasons is the chemistry process. Interannual variability of EASM can impact the spatial distribution of ozone through wind in the lower troposphere, cloud cover, and downward shortwave radiation, which affect the transport and chemical formation of ozone. The phenomenon should be addressed when considering the interaction between ozone and the climate in East Asia region.

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 significant change in the distribution of ozone. The occurrence of extremely low ozone (near 100% ozone depletion) has been declining significantly in favor of the occurrence of low ozone (80-90% ozone depletion). Finally the potential for continuation of this attribution method in the light of the currently available and future planned satellite remote sensing capacity will be shortly addressed.

The Role of Lightning in Controlling Interannual Variability of Tropical Tropospheric Ozone and OH and its Implications for Climate

NASA Technical Reports Server (NTRS)

Murray, Lee T.; Jacob, Daniel J.; Logan, Jennifer A.; Hudman, Rynda C.; Koshak, William J.

2012-01-01

Nitrogen oxides (NO(x) = NO + NO2) produced by lightning make a major contribution to the production of the dominant tropospheric oxidants (OH and ozone). These oxidants control the lifetime of many trace gases including long-lived greenhouse gases, and control the source-receptor relationship of inter-hemispheric pollutant transport. Lightning is affected by meteorological variability, and therefore represents a potentially important tropospheric chemistry-climate feedback. Understanding how interannual variability (IAV) in lightning affects IAV in ozone and OH in the recent past is important if we are to predict how oxidant levels may change in a future warmer climate. However, lightning parameterizations for chemical transport models (CTMs) show low skill in reproducing even climatological distributions of flash rates from the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) satellite instruments. We present an optimized regional scaling algorithm for CTMs that enables sufficient sampling of spatiotemporally sparse satellite lightning data from LIS to constrain the spatial, seasonal, and interannual variability of tropical lightning. We construct a monthly time series of lightning flash rates for 1998-2010 and 35degS-35degN, and find a correlation of IAV in total tropical lightning with El Nino. We use the IAV-constraint to drive a 9-year hindcast (1998-2006) of the GEOS-Chem 3D chemical transport model, and find the increased IAV in LNO(x) drives increased IAV in ozone and OH, improving the model fs ability to simulate both. Although lightning contributes more than any other emission source to IAV in ozone, we find ozone more sensitive to meteorology, particularly convective transport. However, we find IAV in OH to be highly sensitive to lightning NO(x), and the constraint improves the ability of the model to capture the temporal behavior of OH anomalies inferred from observations of methyl chloroform and other gases. The sensitivity of OH is explained using photochemical reaction rates which show a "magnification" effect of the initial lightning NO perturbation on OH primary production, HO(x) recycling, and OH loss frequencies. This influence on OH may represent a negative feedback, if lightning increases in a warming world..

Source attribution of interannual variability of tropospheric ozone over the southern hemisphere

NASA Astrophysics Data System (ADS)

Liu, J.; Rodriguez, J. M.; Logan, J. A.; Steenrod, S. D.; Douglass, A. R.; Olsen, M. A.; Wargan, K.; Ziemke, J. R.

2015-12-01

Both model simulations and GMAO assimilated ozone product derived from OMI/MLS show a high tropospheric ozone column centered over the south Atlantic from the equator to 30S. This ozone maximum extends eastward to South America and the southeast Pacific; it extends southwestward to southern Africa, south Indian Ocean. In this study, we use hindcast simulations from the GMI model of tropospheric and stratospheric chemistry, driven by assimilated MERRA meteorological fields, to investigate the factors controlling the interannual variations (IAV) of this ozone maximum during the last two decades. We also use various GMI tracer diagnostics, including a stratospheric ozone tracer to tag the impact of stratospheric ozone, and a tagged CO tracer to track the emission sources, to ascertain the contribution of difference processes to IAV in ozone at different altitudes, as well as partial columns above different pressure level. Our initial model analysis suggests that the IAV of the stratospheric contribution plays a major role on in the IAV of the upper tropospheric ozone and explains a large portion of variance during its winter season. Over the south Atlantic region, the IAV of surface emissions from both South America and southern Africa also contribute significantly to the IAV of ozone, especially in the middle and lower troposphere

Investigations of Stratosphere-Troposphere Exchange of Ozone Derived From MLS Observations

NASA Technical Reports Server (NTRS)

Olsen, Mark A.; Schoeberl, Mark R.; Ziemke, Jerry R.

2006-01-01

Daily high-resolution maps of stratospheric ozone have been constructed using observations by MLS combined with trajectory information. These fields are used to determine the extratropical stratosphere-troposphere exchange (STE) of ozone for the year 2005 using two diagnostic methods. The resulting two annual estimates compare well with past model- and observational-based estimates. Initial analyses of the seasonal characteristics indicate that significant STE of ozone in the polar regions occurs only during spring and early summer. We also examine evidence that the Antarctic ozone hole is responsible for a rapid decrease in the rate of ozone STE during the SH spring. Subtracting the high-resolution stratospheric ozone fiom OMI total column measurements creates a high-resolution tropospheric ozone residual (HTOR) product. The HTOR fields are compared to the spatial distribution of the ozone STE. We show that the mean tropospheric ozone maxima tend to occur near locations of significant ozone STE. This suggests that STE may be responsible for a significant fraction of many mean tropospheric ozone anomalies.

Characterizing the seasonal cycle and vertical structure of ozone in Paris, France using four years of ground based LIDAR measurements in the lowermost troposphere

NASA Astrophysics Data System (ADS)

Klein, Amélie; Ancellet, Gérard; Ravetta, François; Thomas, Jennie L.; Pazmino, Andrea

2017-10-01

Systematic ozone LIDAR measurements were completed during a 4 year period (2011-2014) in Paris, France to study the seasonal variability of the vertical structure of ozone in the urban boundary layer. In addition, we use in-situ measurements from the surface air quality network that is located in Paris (AIRPARIF). Specifically, we use ozone and NO2 measurements made at two urban stations: Paris13 (60 m ASL) and the Eiffel Tower (310 m ASL) to validate and interpret the LIDAR profiles. Remote sensed tropospheric NO2 integrated columns from the SAOZ instrument located in Paris are also used to interpret ozone measurements. Comparison between ozone LIDAR measurements averaged from 250 m to 500 m and the Eiffel Tower in-situ measurements shows that the accuracy of the LIDAR (originally ±14 μg·m-3) is significantly improved (±7 μg·m-3) when a small telescope with a wide angular aperture is used. Results for the seasonal cycle of the ozone vertical gradient are found to be similar using two methods: (1) measured differences between AIRPARIF stations with measurements at 60 m ASL and 310 m ASL and (2) using LIDAR profiles from 300 m to the top of the Planetary Boundary Layer (PBL). Ozone concentrations measured by the LIDAR increase with altitude within the PBL, with a steeper gradient in winter (60 μg·m-3·km-1) and a less strong gradient in summer (20 μg·m-3·km-1). Results show that in winter, there is a sharp positive gradient of ozone at the surface, which is explained by ozone titration by NO combined with increased atmospheric stability in winter. In the afternoon during summer, photochemistry and vertical mixing are large enough to compensate for ozone titration near the surface, where NOx is emitted, and there is no gradient in ozone observed. In contrast, in the summer during the morning, ozone has a sharper positive vertical gradient similar to the winter values. Comparison of the vertically averaged ozone concentrations up to (0-3 km) and urban layer (0-310 m) ozone concentrations shows that the ratio between these two quantities is the largest in summer (86%) and the lowest in winter (49%). We conclude that satellite measurements that represent the 0-3 km integrated ozone column are not necessarily a good proxy for surface ozone and may lead to incorrect conclusions about the surface ozone seasonal variability. The ratio between the urban layer NO2 average concentration and the boundary layer NO2 average concentration obtained from SAOZ NO2 tropospheric columns is always less than 50%, meaning NO2 does not decrease linearly in the PBL, but with a sharper decrease close to the surface.

A cloud-ozone data product from Aura OMI and MLS satellite measurements

NASA Astrophysics Data System (ADS)

Ziemke, Jerald R.; Strode, Sarah A.; Douglass, Anne R.; Joiner, Joanna; Vasilkov, Alexander; Oman, Luke D.; Liu, Junhua; Strahan, Susan E.; Bhartia, Pawan K.; Haffner, David P.

2017-11-01

Ozone within deep convective clouds is controlled by several factors involving photochemical reactions and transport. Gas-phase photochemical reactions and heterogeneous surface chemical reactions involving ice, water particles, and aerosols inside the clouds all contribute to the distribution and net production and loss of ozone. Ozone in clouds is also dependent on convective transport that carries low-troposphere/boundary-layer ozone and ozone precursors upward into the clouds. Characterizing ozone in thick clouds is an important step for quantifying relationships of ozone with tropospheric H2O, OH production, and cloud microphysics/transport properties. Although measuring ozone in deep convective clouds from either aircraft or balloon ozonesondes is largely impossible due to extreme meteorological conditions associated with these clouds, it is possible to estimate ozone in thick clouds using backscattered solar UV radiation measured by satellite instruments. Our study combines Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) satellite measurements to generate a new research product of monthly-mean ozone concentrations in deep convective clouds between 30° S and 30° N for October 2004-April 2016. These measurements represent mean ozone concentration primarily in the upper levels of thick clouds and reveal key features of cloud ozone including: persistent low ozone concentrations in the tropical Pacific of ˜ 10 ppbv or less; concentrations of up to 60 pphv or greater over landmass regions of South America, southern Africa, Australia, and India/east Asia; connections with tropical ENSO events; and intraseasonal/Madden-Julian oscillation variability. Analysis of OMI aerosol measurements suggests a cause and effect relation between boundary-layer pollution and elevated ozone inside thick clouds over landmass regions including southern Africa and India/east Asia.

Tropospheric Ozone Pollution Transport Traced from the TOMS (Total Ozone Mapping Spectrometer) Instrument During the Nashville-1999 Campaign

NASA Technical Reports Server (NTRS)

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

2000-01-01

Over the past several years, we have developed two new tropospheric ozone retrievals from the TOMS (Total Ozone Mapping Spectrometer) satellite instrument that are of sufficient resolution to follow pollution episodes. The modified-residual technique [Hudson and Thompson, 1998; Thompson and Hudson, 1999] uses v. 7 TOMS total ozone and is applicable to tropical regimes in which the wave-one pattern in total ozone is observed. The TOMS-direct method [("TDOT" = TOMS Direct Ozone in the Troposphere; Frolov et al., 2000] represents a new algorithm that uses TOMS radiances directly (i.e., not previously processed for TOMS ozone) to extract tropospheric ozone in regions of constant stratospheric ozone and tropospheric ozone displaying high mixing ratios and variability characteristic of pollution. These events tend to occur in certain meteorological regimes. For example, mid-latitude pollution usually occurs on the backside of subtropical fronts, as low pv, usually moist air intrudes to the extra-tropics. July 1999 was a month characterized by robust pollution in the eastern US, with high ozone, as detected by TOMS, originating over south central states and moving up the Atlantic seaboard. This corresponds to 50-80 DU in tropospheric ozone column depth. In most cases, further transport occurred to the North Atlantic, with ozone plumes traveling to western Europe in 4-5 days. Examples of high ozone and transit across boundaries within the US, as well as US->Europe, give a regional context for model results and field measurements taken in the SE US during the Nashville-1999 campaign period. Validation of the TDOT maps is made with ozonesondes taken during that time. TDOT maps also show ozone pollution from Asia traveling to the western US in July 1999.

A Cloud-Ozone Data Product from Aura OMI and MLS Satellite Measurements.

PubMed

Ziemke, Jerald R; Strode, Sarah A; Douglass, Anne R; Joiner, Joanna; Vasilkov, Alexander; Oman, Luke D; Liu, Junhua; Strahan, Susan E; Bhartia, Pawan K; Haffner, David P

2017-01-01

Ozone within deep convective clouds is controlled by several factors involving photochemical reactions and transport. Gas-phase photochemical reactions and heterogeneous surface chemical reactions involving ice, water particles, and aerosols inside the clouds all contribute to the distribution and net production and loss of ozone. Ozone in clouds is also dependent on convective transport that carries low troposphere/boundary layer ozone and ozone precursors upward into the clouds. Characterizing ozone in thick clouds is an important step for quantifying relationships of ozone with tropospheric H 2 O, OH production, and cloud microphysics/transport properties. Although measuring ozone in deep convective clouds from either aircraft or balloon ozonesondes is largely impossible due to extreme meteorological conditions associated with these clouds, it is possible to estimate ozone in thick clouds using backscattered solar UV radiation measured by satellite instruments. Our study combines Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) satellite measurements to generate a new research product of monthly-mean ozone concentrations in deep convective clouds between 30°S to 30°N for October 2004 - April 2016. These measurements represent mean ozone concentration primarily in the upper levels of thick clouds and reveal key features of cloud ozone including: persistent low ozone concentrations in the tropical Pacific of ~10 ppbv or less; concentrations of up to 60 pphv or greater over landmass regions of South America, southern Africa, Australia, and India/east Asia; connections with tropical ENSO events; and intra-seasonal/Madden-Julian Oscillation variability. Analysis of OMI aerosol measurements suggests a cause and effect relation between boundary layer pollution and elevated ozone inside thick clouds over land-mass regions including southern Africa and India/east Asia.

Technical note: Examining ozone deposition over seawater

EPA Science Inventory

Surface layer resistance plays an important role in determining ozone deposition velocity over sea-water and can be influenced by chemical interactions at the air-water interface. Here, we examine the effect of chemical interactions of iodide, dimethylsulfide, dissolved organic c...

Measurements of Vertical Profiles of Turbulence, Temperature, Ozone, Aerosols, and BrO over Sea Ice and Tundra Snowpack during BROMEX

NASA Astrophysics Data System (ADS)

Shepson, P.; Caulton, D.; Cambaliza, M. L.; Dhaniyala, S.; Fuentes, J. D.; General, S.; Halfacre, J. W.; Nghiem, S. V.; Perez Perez, L.; Peterson, P. K.; Platt, U.; Pohler, D.; Pratt, K. A.; Simpson, W. R.; Stirm, B.; Walsh, S. J.; Zielcke, J.

2012-12-01

During the BROMEX field campaign of March 2012, we conducted measurements of boundary layer structure, ozone, BrO and aerosol, from a light, twin-engine aircraft during eleven flights originating from Barrow, AK. Flights were conducted over the sea ice in the Beaufort and Chukchi Seas, and over the tundra from Barrow to the Brooks Range, with vertical profiles covering altitudes from the surface to 3.5km in the free troposphere. Flights over the course of one month allowed a variety of sea ice conditions, including open water, nilas, first year sea ice, and frost flowers, to be examined over the Chukchi Sea. Atmospheric turbulence was measured using a calibrated turbulence probe, which will enable characterization of both the structure and turbulence of the Arctic boundary layer. Ozone was measured using a 2B UV absorption instrument. A GRIMM optical particle counter was used to measure 0.25-4 μm sized aerosol particles. The MAX-DOAS instrument enabled measurements of BrO vertical profiles. The aircraft measurements can be used to connect the surface measurements of ozone and BrO from the "Icelander" buoys, and the surface sites at Barrow, with those measured on the aircraft. Here we will discuss the spatial variability/coherence in these data. A major question that will be addressed using these data is the extent to which bromine is activated through reactions at the snowpack/ice surface versus the surface of aerosols. Here we will present a preliminary analysis of the relationships between snow/ice surface types, aerosol size-resolved number concentrations, and the vertical profiles of ozone and BrO.

Development of a Climate Record of Tropospheric and Stratospheric Column Ozone from Satellite Remote Sensing: Evidence of an Early Recovery of Global Stratospheric Ozone

NASA Technical Reports Server (NTRS)

Ziemke, Jerald R.; Chandra, Sushil

2012-01-01

Ozone data beginning October 2004 from the Aura Ozone Monitoring Instrument (OMI) and Aura Microwave Limb Sounder (MLS) are used to evaluate the accuracy of the Cloud Slicing technique in effort to develop long data records of tropospheric and stratospheric ozone and for studying their long-term changes. Using this technique, we have produced a 32-yr (1979-2010) long record of tropospheric and stratospheric column ozone from the combined Total Ozone Mapping Spectrometer (TOMS) and OMI. Analyses of these time series suggest that the quasi-biennial oscillation (QBO) is the dominant source of inter-annual variability of stratospheric ozone and is clearest in the Southern Hemisphere during the Aura time record with related inter-annual changes of 30- 40 Dobson Units. Tropospheric ozone for the long record also indicates a QBO signal in the tropics with peak-to-peak changes varying from 2 to 7 DU. The most important result from our study is that global stratospheric ozone indicates signature of a recovery occurring with ozone abundance now approaching the levels of year 1980 and earlier. The negative trends in stratospheric ozone in both hemispheres during the first 15 yr of the record are now positive over the last 15 yr and with nearly equal magnitudes. This turnaround in stratospheric ozone loss is occurring about 20 yr earlier than predicted by many chemistry climate models. This suggests that the Montreal Protocol which was first signed in 1987 as an international agreement to reduce ozone destroying substances is working well and perhaps better than anticipated.

Processes Understanding of Decadal Climate Variability

NASA Astrophysics Data System (ADS)

Prömmel, Kerstin; Cubasch, Ulrich

2016-04-01

The realistic representation of decadal climate variability in the models is essential for the quality of decadal climate predictions. Therefore, the understanding of those processes leading to decadal climate variability needs to be improved. Several of these processes are already included in climate models but their importance has not yet completely been clarified. The simulation of other processes requires sometimes a higher resolution of the model or an extension by additional subsystems. This is addressed within one module of the German research program "MiKlip II - Decadal Climate Predictions" (http://www.fona-miklip.de/en/) with a focus on the following processes. Stratospheric processes and their impact on the troposphere are analysed regarding the climate response to aerosol perturbations caused by volcanic eruptions and the stratospheric decadal variability due to solar forcing, climate change and ozone recovery. To account for the interaction between changing ozone concentrations and climate a computationally efficient ozone chemistry module is developed and implemented in the MiKlip prediction system. The ocean variability and air-sea interaction are analysed with a special focus on the reduction of the North Atlantic cold bias. In addition, the predictability of the oceanic carbon uptake with a special emphasis on the underlying mechanism is investigated. This addresses a combination of physical, biological and chemical processes.

A Global Climatology of Tropospheric and Stratospheric Ozone Derived from Aura OMI and MLS Measurements

NASA Technical Reports Server (NTRS)

Ziemke, J.R.; Chandra, S.; Labow, G.; Bhartia, P. K.; Froidevaux, L.; Witte, J. C.

2011-01-01

A global climatology of tropospheric and stratospheric column ozone is derived by combining six years of Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) ozone measurements for the period October 2004 through December 2010. The OMI/MLS tropospheric ozone climatology exhibits large temporal and spatial variability which includes ozone accumulation zones in the tropical south Atlantic year-round and in the subtropical Mediterranean! Asia region in summer months. High levels of tropospheric ozone in the northern hemisphere also persist in mid-latitudes over the eastern North American and Asian continents extending eastward over the Pacific Ocean. For stratospheric ozone climatology from MLS, largest ozone abundance lies in the northern hemisphere in the latitude range 70degN-80degN in February-April and in the southern hemisphere around 40degS-50degS during months August-October. The largest stratospheric ozone abundances in the northern hemisphere lie over North America and eastern Asia extending eastward across the Pacific Ocean and in the southern hemisphere south of Australia extending eastward across the dateline. With the advent of many newly developing 3D chemistry and transport models it is advantageous to have such a dataset for evaluating the performance of the models in relation to dynamical and photochemical processes controlling the ozone distributions in the troposphere and stratosphere.

The Antarctic Ozone Hole: New Approaches for Detection of the Onset of Stratospheric Ozone Recovery

NASA Astrophysics Data System (ADS)

de Laat, J.; van Weele, M.; van der A, R. J.

2016-12-01

An important aspect of human influences on climate concerns the Antarctic ozone hole, the strong thinning of the thickness of the ozone layer during springtime over Antarctica, first observed in the early 1980s. Antarctic stratospheric ozone is expected to fully recover in the second half of the 21st century because of policy measures to eliminate emissions of ozone depleting substances. Identification of the onset of this recovery would mark an important scientific and political milestone, but has remained difficult so far owing to natural climate variability and methodological ambiguities. In this presentation, we will first give a brief introduction to methods that have been used in the past to try to identify the onset of recovery, and discuss their shortcomings and ambiguities. Secondly, we introduce and discuss a several observations-based new approaches for ozone recovery detection in the Antarctic Ozone Hole that we have developed, explain why we believe these methods are more robust than standard methods, and outline how they circumvent crucial pitfalls of the previously used methods. Finally, we present our analyses, showing that these new approaches applied to various sets of remote sensing observations provide the best evidence to date that that ozone destruction within the Antarctic Ozone Hole has significantly decreased since approximately the year 2000, and which can be attributed to concurrently decreasing ozone depleting substances.

Evolution of the eastward shift in the quasi-stationary minimum of the Antarctic total ozone column

NASA Astrophysics Data System (ADS)

Grytsai, Asen; Klekociuk, Andrew; Milinevsky, Gennadi; Evtushevsky, Oleksandr; Stone, Kane

2017-02-01

The quasi-stationary pattern of the Antarctic total ozone has changed during the last 4 decades, showing an eastward shift in the zonal ozone minimum. In this work, the association between the longitudinal shift of the zonal ozone minimum and changes in meteorological fields in austral spring (September-November) for 1979-2014 is analyzed using ERA-Interim and NCEP-NCAR reanalyses. Regressive, correlative and anomaly composite analyses are applied to reanalysis data. Patterns of the Southern Annular Mode and quasi-stationary zonal waves 1 and 3 in the meteorological fields show relationships with interannual variability in the longitude of the zonal ozone minimum. On decadal timescales, consistent longitudinal shifts of the zonal ozone minimum and zonal wave 3 pattern in the middle-troposphere temperature at the southern midlatitudes are shown. Attribution runs of the chemistry-climate version of the Australian Community Climate and Earth System Simulator (ACCESS-CCM) model suggest that long-term shifts of the zonal ozone minimum are separately contributed by changes in ozone-depleting substances and greenhouse gases. As is known, Antarctic ozone depletion in spring is strongly projected on the Southern Annular Mode in summer and impacts summertime surface climate across the Southern Hemisphere. The results of this study suggest that changes in zonal ozone asymmetry accompanying ozone depletion could be associated with regional climate changes in the Southern Hemisphere in spring.

Trends in the Vertical Distribution of Ozone: A Comparison of Two Analyses of Ozonesonde Data

NASA Technical Reports Server (NTRS)

Loogan, J. A.; Megretskaia, I. A.; Miller, A. J.; Tiao, G. C.; Choi, D.; Zhang, L.; Bishop, L.; Stolarski, R.; Labow, G. J.; Hollandsworth, S. M.;

POGO-FAN: Remarkable Empirical Indicators for the Local Chemical Production of Smog- Ozone and NOx-Sensitivity of Air Parcels

NASA Astrophysics Data System (ADS)

Chatfield, R. B.; Browell, E. V.; Brune, W. H.; Crawford, J. H.; Esswein, R.; Fried, A.; Olson, J. R.; Shetter, R. E.; Singh, H. B.

2006-12-01

We propose and evaluate two related and surprisingly simple empirical estimators for the local chemical production term for photochemical ozone; each uses two moderate-technology chemical measurements and a measurement of ultraviolet light. We nickname the techniques POGO-FAN: Production of Ozone by Gauging Oxidation: Formaldehyde and NO. (1) A non-linear function of a single three-factor index-variable, j (HCHO=>rads) [HCHO] [NO] seems to provide a good estimator of the largest single term in the production of smog ozone, the HOO+NO term, over a very wide range of situations. (2) By considering empirical contour plots summarizing isopleths of HOO+NO using j (HCHO=>rads) [HCHO] and [NO] separately as coordinates, we provide a slightly more complex 2-d indicator of smog ozone production that additionally allows an estimate of the NOx-sensitivity or NOx-saturation (i.e., VOC-sensitivity) of sampled air parcels. ~85 to >90 % of the variance is explained. The correspondence to "EKMA" contour plots, estimating afternoon ozone based on morningtime organics and NOx mixes, is not coincidental. We utilize a broad set of urban plume, regionally polluted and cleaner NASA DC-8 PBL samples from the Intercontinental Transport Experiment-North America (INTEX-NA), in which each of the variables was measured, to help establish our relationship. The estimator is described in terms both both of asymptotic smog photochemistry theory; primarily this suggests appropriate statistical approaches which can capture some of the complex interrelations of lower-tropospheric smog mix through correlation of reactive mixture components. HCHO is not only an important source of HOO radicals, but it more important serves as a "gauge" of all photochemical processing of volatile organic compounds. It probably captures information related to coincident VOC sources of various compounds and parallels in photochemical processing. Constrained modeling of observed atmospheric concentrations suggests that the prime source of ozone from HOO+NO reaction and other peroxy radical ozone formation reactions (ROO+NO), thus all ozone production, are closely related. Additionally, modeling allows us to follow ozone production and NOx-sensitivity throughout the varying photolytic cycle.

Operational Production of the Total Ozone Essential Climate Variable as Part of the Copernicus Climate Change Service (C3S)

NASA Astrophysics Data System (ADS)

Lerot, C.; Danckaert, T.; van Gent, J.; Coldewey-Egbers, M.; Loyola, D. G.; Errera, Q.; Spurr, R. J. D.; Garane, K.; Koukouli, M.; Balis, D.; Verhoelst, T.; Granville, J.; Lambert, J. C.; Van Roozendael, M.

2017-12-01

Total ozone is one of the Essential Climate Variables (ECV) operationally produced within the European Copernicus Climate Change Service (C3S), which aims at providing the geophysical information needed to monitor and study our climate system. The C3S total ozone processing chain relies on algorithmic developments realized for the last six years as part of the ESA's Ozone Climate Change Initiative (Ozone_cci) project. The C3S Climate Data Store currently contains a total ozone record based on observations from the nadir UV-Vis hyperspectral spectrometers GOME/ERS-2, SCIAMACHY/Envisat, GOME-2/Metop-A, GOME-2/Metop-B and OMI/Aura, spanning more than 23 years.Individual level-2 datasets were generated with the retrieval algorithm GODFIT (GOME-type Direct FITting). The retrievals are based on a non-linear least squares adjustment of reflectances simulated with radiative transfer tools from the LIDORT suite, to the measured spectra in the Huggins bands (325-335 nm). The inter-sensor consistency and the time stability of those data sets is significantly enhanced with the application of a soft-calibration procedure to the level-1 reflectances, in which GOME and OMI are used together as a long-term reference. Level-2 data sets are then combined to produce the level-3 GOME-type Total Ozone (GTO-ECV) record consisting of homogenized 1°x1° monthly mean grids. The merging procedure corrects for subsisting inter-satellite biases and temporal drifts. Some developments for minimizing sampling errors have also been recently investigated and will be discussed. Total ozone level-2 and level-3 data sets are regularly verified and validated by independent measurements both from space (independent algorithms and/or instruments) and ground (Brewer/Dobson/SAOZ) and their excellent quality and stability, as well as their consistency with other long-term total ozone data sets will be illustrated here. In future, in addition to be continuously extended in time, the C3S total ozone record will also incorporate new sensors such as OMPS aboard Suomi NPP or TROPOMI/S5p.

PLASMA AND LUNG MACROPHAGE CAROTENOID RESPONSIVENESS TO SUPPLEMENTATION AND OZONE EXPOSURE IN HUMANS

EPA Science Inventory

OBJECTIVE:: To examine the effect of ozone exposure and vegetable juice supplementation on plasma and lung macrophage concentrations of carotenoids. DESIGN:: A randomized trial. SETTING:: Subjects were exposed to ambient air prior to antioxidant supplementation and to ozone after...

Opposing effects of particle pollution, ozone, and ambient temperature on arterial blood pressure.

PubMed

Hoffmann, Barbara; Luttmann-Gibson, Heike; Cohen, Allison; Zanobetti, Antonella; de Souza, Celine; Foley, Christopher; Suh, Helen H; Coull, Brent A; Schwartz, Joel; Mittleman, Murray; Stone, Peter; Horton, Edward; Gold, Diane R

2012-02-01

Diabetes increases the risk of hypertension and orthostatic hypotension and raises the risk of cardiovascular death during heat waves and high pollution episodes. We examined whether short-term exposures to air pollution (fine particles, ozone) and heat resulted in perturbation of arterial blood pressure (BP) in persons with type 2 diabetes mellitus (T2DM). We conducted a panel study in 70 subjects with T2DM, measuring BP by automated oscillometric sphygmomanometer and pulse wave analysis every 2 weeks on up to five occasions (355 repeated measures). Hourly central site measurements of fine particles, ozone, and meteorology were conducted. We applied linear mixed models with random participant intercepts to investigate the association of fine particles, ozone, and ambient temperature with systolic, diastolic, and mean arterial BP in a multipollutant model, controlling for season, meteorological variables, and subject characteristics. An interquartile increase in ambient fine particle mass [particulate matter (PM) with an aerodynamic diameter of ≤ 2.5 μm (PM2.5)] and in the traffic component black carbon in the previous 5 days (3.54 and 0.25 μg/m3, respectively) predicted increases of 1.4 mmHg [95% confidence interval (CI): 0.0, 2.9 mmHg] and 2.2 mmHg (95% CI: 0.4, 4.0 mmHg) in systolic BP (SBP) at the population geometric mean, respectively. In contrast, an interquartile increase in the 5-day mean of ozone (13.3 ppb) was associated with a 5.2 mmHg (95% CI: -8.6, -1.8 mmHg) decrease in SBP. Higher temperatures were associated with a marginal decrease in BP. In subjects with T2DM, PM was associated with increased BP, and ozone was associated with decreased BP. These effects may be clinically important in patients with already compromised autoregulatory function.

Ozone delignification of pine and eucalyptus kraft pulps. 2: Selectivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simoes, R.M.S.; Castro, J.A.A.M.

1999-12-01

The selectivity of ozone in the delignification of unbleached pine and eucalyptus kraft pulps is studied at ultralow consistency in a stirred reactor under closely controlled experimental conditions. The effect of several operating variables is analyzed, but special attention is paid to the depolymerization rate of polysaccharides with the particular goal of evaluating the influence of the lignin contents on its kinetics. By using substantially different ozone concentrations in the pulp suspension and different reaction temperatures, it is possible to show that ozone selectivity can only be slightly improved by manipulating these operating variables. Furthermore, for the same type ofmore » material, it was observed that the initial rate of delignification plays the most important role on selectivity. In fact, for a given pulp, selectivity decreases with a decrease of the initial lignin contents, and such results can be well justified by the corresponding reduction of the initial rates of delignification. To further investigate the effect of lignin on pulp degradation, experiments were carried out at 4 C between ozone and holocellulose, which represent the polysaccharides of the unbleached pulps. The results suggest that molecular ozone can be responsible for an important part of the polysaccharides depolymerization during the delignification process. Moreover, the comparison of the kinetic behavior of holocellulose and of the corresponding unbleached pulp also reveals that the presence of lignin in the pulp enhances both the depolymerization and the degradation rates of polysaccharides.« less

Exceedance of PM10 and ozone concentration limits in Germany - Spatial variability and influence of climate

NASA Astrophysics Data System (ADS)

Heidenreich, Majana; Bernhofer, Christian

2014-05-01

High concentrations of particulate matter (PM) and ground-level ozone (O3) have negative impacts on human health, e.g., increased risk of respiratory disease, and the environment. European Union (EU) air policy and air quality standards led to continuously reduced air pollution problems in recent decades. Nevertheless, the limit values for PM10 (particles with diameter of 10 micrometers or less) and ozone - defined by the directive 2008/50/EC of the European Parliament - are still exceeded frequently. Poor air quality and the exceedance of limits result mainly from the combination of high emissions and unfavourable weather conditions. Datasets from German monitoring stations are used to describe the spatial and temporal variability of the exceedance of concentration limits for PM10 and ozone for the federal states of Germany. Time series are analysed for the period 2000-2012 for PM10 and for the period 1990-2012 for ozone. Furthermore, the influence of weather patterns on the exceedance of concentration limits on a regional scale was investigated. Here, the "objective weather types" of the German Weather Service were used. As expected, for most regions anticyclonic weather types (with a negative cyclonality index for the two levels 950 and 500 hPa) show a high frequency on exeedance days, both for PM10 and ozone. The results could contribute to estimate the future exceedance frequency of concentration limits and to develop possible countermeasures.

Understanding and improving global crop response to ozone pollution

USDA-ARS?s Scientific Manuscript database

Concentrations of ground-level ozone ([O3]) over much of the Earth’s land surface have more than doubled since pre-industrial times. The air pollutant is highly variable over time and space, which makes it difficult to assess the average agronomic and economic impacts of the pollutant as well as to ...

Modeling impacts of CO2, ozone, and climate change on tree growth

Treesearch

George E. Host; Gary W. Theseira; J. G. Isebrands

1996-01-01

Understanding the influence of ozone, CO2, and changing climatic regimes on basic plant physiological processes is essential for predicting the response of forest ecosystems. To understand the relationships among these interacting factors, in the face of genetic and other environmental variability, requires a means of synthesis. Physiological...

Estimating North American background ozone in U.S. surface air with two independent global models: Variability, uncertainties, and recommendations

EPA Science Inventory

Accurate estimates for North American background (NAB) ozone (O3) in surface air over the United States are needed for setting and implementing an attainable national O3 standard. These estimates rely on simulations with atmospheric chemistry-transport models that set North Amer...

The Variable Effects of Ozone and/or Diesel Particulate Inhalation Exposure on Allergic Airways Responses in Mice

EPA Science Inventory

Exposure to diesel exhaust particle matter (DEP) associated with the combustion of diesel fuel exacerbates asthma. Likewise, similar effects have been reported with exposure to the oxidizing air pollutant ozone (O₃). Since levels of both pollutants in ambient air are e...

Technical note: Examining ozone deposition over seawater

NASA Astrophysics Data System (ADS)

Sarwar, Golam; Kang, Daiwen; Foley, Kristen; Schwede, Donna; Gantt, Brett; Mathur, Rohit

2016-09-01

Surface layer resistance plays an important role in determining ozone deposition velocity over sea-water and can be influenced by chemical interactions at the air-water interface. Here, we examine the effect of chemical interactions of iodide, dimethylsulfide, dissolved organic carbon, and bromide in seawater on ozone deposition. We perform a series of simulations using the hemispheric Community Multiscale Air Quality model for summer months in the Northern Hemisphere. Our results suggest that each chemical interaction enhances the ozone deposition velocity and decreases the atmospheric ozone mixing ratio over seawater. Iodide enhances the median deposition velocity over seawater by 0.023 cm s-1, dissolved organic carbon by 0.021 cm s-1, dimethylsulfide by 0.002 cm s-1, and bromide by ∼0.0006 cm s-1. Consequently, iodide decreases the median atmospheric ozone mixing ratio over seawater by 0.7 ppb, dissolved organic carbon by 0.8 ppb, dimethylsulfide by 0.1 ppb, and bromide by 0.02 ppb. In a separate model simulation, we account for the effect of dissolved salts in seawater on the Henry's law constant for ozone and find that it reduces the median deposition velocity by 0.007 cm s-1 and increases surface ozone mixing ratio by 0.2 ppb. The combined effect of these processes increases the median ozone deposition velocity over seawater by 0.040 cm s-1, lowers the atmospheric ozone mixing ratio by 5%, and slightly improves model performance relative to observations.

A computer program for the determination of the solar risk in Argentina by dermatologists employing NASA TOMS satellite ozone data as a key geophysical variable

NASA Astrophysics Data System (ADS)

Piacentini, R.; Cede, A.; Luccini, E.; Stengel, F.

The connection between skin cancer and solar ultraviolet radiation has been well documented (i.e., UNEP report "Environmental Effects of Ozone Depletion. 1998 Assessment"). In this work wepresent a computer software that can be used by dermatologists for determining the risk of persons that are exposed to solar UV radiation incident in Argentina, a country largely extended from low (tropical) to high southern hemisphere latitudes. In particular, its spectral distribution weighted by the CIE standard erythemal action spectrum and integrated in wavelength usually called "erythemal irradiance", is calculated including the following geophysical variables: ozone, solar elevation, Sun-Earth distance, altitude, aerosol and albedo. Other variables that have less influence in the final results are the vertical ozone, aerosol, pressure and temperature profiles, the extraterrestrial spectral solar UV irradiance and the ozone photoabsorption cross section. The ozone total column was obtained from the corresponding seasonal and latitudinal climatological NASA TOMS satellite data, including monthly averages, standard deviations and tendencies for the particular geographical situation of Argentina. The program considers also the different skin types, in order to determine the skin risk without or with a sunscreen protection at each moment of the day and for different days of the year. We present the program output for typical examples of persons exposed in extreme conditions, like in the high altitude tropical Puna of Atacama desert in the North- West, or when the ozone hole event overpasses Ushuaia in the South, as well as in Buenos Aires, the largest populated city in the country and one of the megacities of the world. The availability of a large satellite ozone data set gives us the possibility to make a clear sky day solar risk forecast for all the year, that can be applied in all places of the country. This work was made possible through a collaboration between the Argentina Skin Cancer Foundation, the Institute of Physics Rosario (CONICET - National University of Rosario) and the Institute of Medical Physics of the University of Innsbruck, Austria. With this support and the work of physicians and physicists, now dermatologists as well as health authorities and educators can make a reliable (scientific) prediction of the risk due to solar exposure, in order to prevent health problems induced by solar UV radiation.

Vitamin E antagonizes ozone-induced asthma exacerbation in Balb/c mice through the Nrf2 pathway.

PubMed

Duan, Liju; Li, Jinquan; Ma, Ping; Yang, Xu; Xu, Shunqing

2017-09-01

Millions of people are regularly exposed to ozone, a gas known to contribute significantly to worsening the symptoms of patients with asthma. However, the mechanisms underlying these ozone exacerbation effects are not fully understood. In this study, we examined the exacerbation effect of ozone in OVA-induced asthma mice and tried to demonstrate the protective mechanism of vitamin E (VE). An asthma mouse model was established, and used to identify the exacerbating effects of ozone by assessing cytokine and serum immunoglobulin concentrations, airway leukocyte infiltration, histopathological changes in lung tissues, and airway hyper-responsiveness. We then determined the amount of reactive oxygen species (ROS) accumulated, the extent to which VE induced ROS elimination, and examined the antagonistic effects of VE on the ozone-induced exacerbating effects. This study showed that 1-ppm ozone exposure could exacerbate OVA-induced asthma in mice. More importantly we found that ozone induced oxidative stress in asthmatic airways may lead to the inhibition of Nuclear factor-erythroid 2-related factor 2 (Nrf2), and may subsequently induce even more exaggerated oxidative stress associated with asthma exacerbation. Through VE induced Nrf2 activation and the subsequent increase in Nrf2 target protein expression, this study suggests a novel mechanism for alleviating ozone exacerbated asthma symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Children's and adults' knowledge and models of reasoning about the ozone layer and its depletion

NASA Astrophysics Data System (ADS)

Leighton, Jacqueline P.; Bisanz, Gay L.

2003-01-01

As environmental concepts, the ozone layer and ozone hole are important to understand because they can profoundly influence our health. In this paper, we examined: (a) children's and adults' knowledge of the ozone layer and its depletion, and whether this knowledge increases with age' and (b) how the 'ozone layer' and 'ozone hole' might be structured as scientific concepts. We generated a standardized set of questions and used it to interview 24 kindergarten students, 48 Grade 3 students, 24 Grade 5 students, and 24 adults in university, in Canada. An analysis of participants' responses revealed that adults have more knowledge than children about the ozone layer and ozone hole, but both adults and children exhibit little knowledge about protecting themselves from the ozone hole. Moreover, only some participants exhibited 'mental models' in their conceptual understanding of the ozone layer and ozone hole. The implications of these results for health professionals, educators, and scientists are discussed.

Synoptic meteorological conditions associated with high spring and summer ozone levels at a rural site in the Eastern Mediterranean

NASA Astrophysics Data System (ADS)

Kalabokas, Pavlos; Repapis, Christos; Mihalopoulos, Nikos; Zerefos, Christos

2017-04-01

For the identification of the nature of spring and summertime ozone episodes, rural ozone measurements from the Eastern Mediterranean station of Finokalia-Crete, Greece during the first 4-year period of its record (1998-2001) have been analyzed with emphasis on periods of high ozone concentrations, according to the daily variation of the afternoon (12:00 - 18:00) ozone values. For the 7% highest spring and summertime ozone episodes composite NOAA/ESRL reanalysis maps of various meteorological parameters and/or their anomalies (geopotential height, specific humidity, vertical wind velocity omega, vector wind speed and temperature) have been examined together with their corresponding HYSPLIT back trajectories. This work is a continuation of a previous first approach regarding summer highest and lowest surface ozone episodes in Finokalia and other Central and Eastern Mediterranean stations (Kalabokas et al., 2008), which is now extended to more meteorological parameters and higher pressure levels. The results show that the examined synoptic meteorological condition during springtime ozone episodes over the Eastern Mediterranean station of Finokalia are quite similar with those conditions during high ozone springtime episodes observed at rural stations over the Western Mediterranean (Kalabokas et al., 2016). On the other hand the summer time synoptic conditions corresponding to highest surface ozone episodes at Finokalia are comparable with the conditions encountered during highest ozone episodes in the lower troposphere following analysis of MOZAIC vertical profiles over the Aegean Sea and the Eastern Mediterranean (Kalabokas et al., 2015 and references therein). During the highest ozone episodes, for both examined seasons, the transport of tropospheric ozone-rich air masses through atmospheric subsidence influences significantly the boundary layer and surface ozone concentrations. In particular, the geographic areas with observed tropospheric subsidence seem to be the transition regions between high and low pressure synoptic meteorological systems. References Kalabokas, P. D., Mihalopoulos, N., Ellul, R., Kleanthous, S., and Repapis, C. C., 2008. An investigation of the meteorological and photochemical factors influencing the background rural and marine surface ozone levels in the Central and Eastern Mediterranean, Atmos. Environ., 42, 7894-7906. Kalabokas P. D., Thouret V., Cammas J.-P., Volz-Τhomas A., Boulanger D., Repapis C.C., 2015. The geographical distribution of meteorological parameters associated with high and low summer ozone levels in the lower troposphere and the boundary layer over the eastern Mediterranean (Cairo case), Tellus B, 67, 27853, http://dx.doi.org/10.3402/tellusb.v67.27853. Kalabokas P., J. Hjorth, G. Foret, G. Dufour, M. Eremenko, G. Siour, J. Cuesta, M. Beekmann, 2016. An investigation on the origin of regional spring time ozone episodes in the Western Mediterranean and Central Europe. Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-615.

Land use regression modeling of ultrafine particles, ozone, nitrogen oxides and markers of particulate matter pollution in Augsburg, Germany.

PubMed

Wolf, Kathrin; Cyrys, Josef; Harciníková, Tatiana; Gu, Jianwei; Kusch, Thomas; Hampel, Regina; Schneider, Alexandra; Peters, Annette

2017-02-01

Important health relevance has been suggested for ultrafine particles (UFP) and ozone, but studies on long-term effects are scarce, mainly due to the lack of appropriate spatial exposure models. We designed a measurement campaign to develop land use regression (LUR) models to predict the spatial variability focusing on particle number concentration (PNC) as indicator for UFP, ozone and several other air pollutants in the Augsburg region, Southern Germany. Three bi-weekly measurements of PNC, ozone, particulate matter (PM 10 , PM 2.5 ), soot (PM 2.5 abs) and nitrogen oxides (NO x , NO 2 ) were performed at 20 sites in 2014/15. Annual average concentration were calculated and temporally adjusted by measurements from a continuous background station. As geographic predictors we offered several traffic and land use variables, altitude, population and building density. Models were validated using leave-one-out cross-validation. Adjusted model explained variance (R 2 ) was high for PNC and ozone (0.89 and 0.88). Cross-validation adjusted R 2 was slightly lower (0.82 and 0.81) but still indicated a very good fit. LUR models for other pollutants performed well with adjusted R 2 between 0.68 (PM coarse ) and 0.94 (NO 2 ). Contrary to previous studies, ozone showed a moderate correlation with NO 2 (Pearson's r=-0.26). PNC was moderately correlated with ozone and PM 2.5 , but highly correlated with NO x (r=0.91). For PNC and NO x , LUR models comprised similar predictors and future epidemiological analyses evaluating health effects need to consider these similarities. Copyright © 2016 Elsevier B.V. All rights reserved.

Convective Distribution of Tropospheric Ozone and Tracers in the Central American ITCZ Region: Evidence from Observations During TC4

NASA Technical Reports Server (NTRS)

Avery, Melody; Twohy, Cynthia; MCabe, David; Joiner, Joanna; Severance, Kurt; Atlas, Eliot; Blake, Donald; Bui, T. P.; Crounse, John; Dibb, Jack;

Tabulations of ambient ozone data obtained by GASP (Global Air Sampling Program) airliners, March 1975 to July 1979

NASA Technical Reports Server (NTRS)

Jasperson, W. H.; Holdeman, J. D.

1984-01-01

Tabulations are given of GASP ambient ozone mean, standard deviation, median, 84th percentile, and 98th percentile values, by month, flight level, and geographical region. These data are tabulated to conform to the temporal and spatial resolution required by FAA Advisory Circular 120-38 (monthly by 2000 ft in altitude by 5 deg in latitude) for climatological data used to show compliance with cabin ozone regulations. In addition seasonal x 10 deg latitude tabulations are included which are directly comparable to and supersede the interim GASP ambient ozone tabulations given in appendix B of FAA-EE-80-43 (NASA TM-81528). Selected probability variations are highlighted to illustrate the spatial and temporal variability of ambient ozone and to compare results from the coarse and fine grid analyses.

Intra-urban spatial variability of surface ozone in Riverside, CA: viability and validation of low-cost sensors

NASA Astrophysics Data System (ADS)

Sadighi, Kira; Coffey, Evan; Polidori, Andrea; Feenstra, Brandon; Lv, Qin; Henze, Daven K.; Hannigan, Michael

2018-03-01

Sensor networks are being more widely used to characterize and understand compounds in the atmosphere like ozone (O3). This study employs a measurement tool, called the U-Pod, constructed at the University of Colorado Boulder, to investigate spatial and temporal variability of O3 in a 200 km2 area of Riverside County near Los Angeles, California. This tool contains low-cost sensors to collect ambient data at non-permanent locations. The U-Pods were calibrated using a pre-deployment field calibration technique; all the U-Pods were collocated with regulatory monitors. After collocation, the U-Pods were deployed in the area mentioned. A subset of pods was deployed at two local regulatory air quality monitoring stations providing validation for the collocation calibration method. Field validation of sensor O3 measurements to minute-resolution reference observations resulted in R2 and root mean squared errors (RMSEs) of 0.95-0.97 and 4.4-5.9 ppbv, respectively. Using the deployment data, ozone concentrations were observed to vary on this small spatial scale. In the analysis based on hourly binned data, the median R2 values between all possible U-Pod pairs varied from 0.52 to 0.86 for ozone during the deployment. The medians of absolute differences were calculated between all possible pod pairs, 21 pairs total. The median values of those median absolute differences for each hour of the day varied between 2.2 and 9.3 ppbv for the ozone deployment. Since median differences between U-Pod concentrations during deployment are larger than the respective root mean square error values, we can conclude that there is spatial variability in this criteria pollutant across the study area. This is important because it means that citizens may be exposed to more, or less, ozone than they would assume based on current regulatory monitoring.

Surface ozone characterization at Larsemann Hills and Maitri, Antarctica.

PubMed

Ali, Kaushar; Trivedi, D K; Sahu, S K

2017-04-15

Data are analyzed in terms of daily average ozone, its diurnal variation and its relation with meteorological parameters like dry bulb temperature (T), wet bulb temperature (T w ), atmospheric pressure and wind speed based on measurement of these parameters at two Indian Antarctic stations (Larsemann Hills, and Maitri) during 28th Indian Scientific Expedition of Antarctica (ISEA) organized during Antarctic summer of the year 2008-09. The work has been carried out to investigate summer time ozone level and its day-to-day and diurnal variability at these coastal locations and to highlight possible mechanism of ozone production and destruction. The result of the analysis indicates that daily average ozone concentration at Larsemann Hills varied from ~13 and ~20ppb with overall average value of ~16ppb and at Maitri, it varied from ~16 and ~21ppb with overall average value of ~18ppb. Photochemistry is found to partially contribute occasionally to the surface layer ozone at both the stations. Lower concentration of ozone at Maitri during beginning of the observational days may be due to destruction of ozone through activated halogens, whereas higher ozone on latter days may be due to photochemistry and advective transport from east to south-east areas. Ozone concentration during blizzard episodes at both the stations is reduced due to slow photochemical production of ozone, its photochemical removal and removal through deposition of ozone molecules on precipitation particles. Diurnal variation of ozone at Larsemann Hills and Maitri has been found to be absent. Copyright © 2017 Elsevier B.V. All rights reserved.

Can Assimilation of Satellite Ozone Data Contribute to the Understanding of the Lower Stratospheric Ozone?

NASA Technical Reports Server (NTRS)

Stajner, I.; Wargan, K.; Pawson, S.; Hayashi, H.; Chang, L.-P.; Rood, R.

2004-01-01

We study the quality of lower stratospheric ozone fields from a three- dimensional global ozone assimilation system. Ozone in this region is important for the forcing of climate, but its global distribution is not fully known because of its large temporal and vertical variability. Modeled fields often have biases due to the inaccurate representation of transport processes in this region with strong gradients. Accurate ozonesonde or satellite occultation measurements have very limited coverage. Nadir measurements, such as those from the Solar Backscatter Ultraviolet/2 (SBUV/2) instrument that provide wide latitudinal coverage, lack the vertical resolution needed to represent sharp vertical features. Limb measurements, such as those from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), provide a finer vertical resolution. We show that assimilation of MIPAS data in addition to SBUV/2 data leads to better estimates of ozone in comparison with independent high quality satellite, aircraft, and ozone sonde measurements. Other modifications to the statistical analysis that have an impact on the lower stratospheric ozone will be mentioned: error covariance modeling and data selection. Direct and indirect impacts of transport and chemistry models will be discussed. Implications for multi-year analyses and short-tern prediction will be addressed.

Convective storms and non-classical low-level jets during high ozone level episodes in the Amazon region: An ARM/GOAMAZON case study

NASA Astrophysics Data System (ADS)

Dias-Junior, Cléo Q.; Dias, Nelson Luís; Fuentes, José D.; Chamecki, Marcelo

2017-04-01

In this work, we investigate the ozone dynamics during the occurrence of both downdrafts associated with mesoscale convective storms and non-classical low-level jets. Extensive data sets, comprised of air chemistry and meteorological observations made in the Amazon region of Brazil over the course of 2014-15, are analyzed to address several questions. A first objective is to investigate the atmospheric thermodynamic and dynamic conditions associated with storm-generated ozone enhancements in the Amazon region. A second objective is to determine the magnitude and the frequency of ground-level ozone enhancements related to low-level jets. Ozone enhancements are analyzed as a function of wind shear, low-level jet maximum wind speed, and altitude of jet core. Strong and sudden increases in ozone levels are associated with simultaneous changes in variables such as horizontal wind speed, convective available potential energy, turbulence intensity and vertical velocity skewness. Rapid increases in vertical velocity skewness give support to the hypothesis that the ozone enhancements are directly related to downdrafts. Low-level jets associated with advancing density currents are often present during and after storm downdrafts that transport ozone-enriched air from aloft to the surface.

Anomalous low tropospheric column ozone over eastern India during the severe drought event of monsoon 2002: a case study.

PubMed

Ghude, Sachin D; Kulkarni, Santosh H; Kulkarni, Pavan S; Kanawade, Vijay P; Fadnavis, Suvarna; Pokhrel, Samir; Jena, Chinmay; Beig, G; Bortoli, D

2011-09-01

The present study is an attempt to examine some of the probable causes of the unusually low tropospheric column ozone observed over eastern India during the exceptional drought event in July 2002. We examined horizontal wind and omega (vertical velocity) anomalies over the Indian region to understand the large-scale dynamical processes which prevailed in July 2002. We also examined anomalies in tropospheric carbon monoxide (CO), an important ozone precursor, and observed low CO mixing ratio in the free troposphere in 2002 over eastern India. It was found that instead of a normal large-scale ascent, the air was descending in the middle and lower troposphere over a vast part of India. This configuration was apparently responsible for the less convective upwelling of precursors and likely caused less photochemical ozone formation in the free troposphere over eastern India in July 2002. The insight gained from this case study will hopefully provide a better understanding of the process controlling the distribution of the tropospheric ozone over the Indian region.

A multivariate auto-regressive combined-harmonics analysis and its application to ozone time series data

NASA Astrophysics Data System (ADS)

Yang, Eun-Su

2001-07-01

A new statistical approach is used to analyze Dobson Umkehr layer-ozone measurements at Arosa for 1979-1996 and Total Ozone Mapping Spectrometer (TOMS) Version 7 zonal mean ozone for 1979-1993, accounting for stratospheric aerosol optical depth (SAOD), quasi-biennial oscillation (QBO), and solar flux effects. A stepwise regression scheme selects statistically significant periodicities caused by season, SAOD, QBO, and solar variations and filters them out. Auto-regressive (AR) terms are included in ozone residuals and time lags are assumed for the residuals of exogenous variables. Then, the magnitudes of responses of ozone to the SAOD, QBO, and solar index (SI) series are derived from the stationary time series of the residuals. These Multivariate Auto-Regressive Combined Harmonics (MARCH) processes possess the following significant advantages: (1)the ozone trends are estimated more precisely than the previous methods; (2)the influences of the exogenous SAOD, QBO, and solar variations are clearly separated at various time lags; (3)the collinearity of the exogenous variables in the regression is significantly reduced; and (4)the probability of obtaining misleading correlations between ozone and exogenous times series is reduced. The MARCH results indicate that the Umkehr ozone response to SAOD (not a real ozone response but rather an optical interference effect), QBO, and solar effects is driven by combined dynamical radiative-chemical processes. These results are independently confirmed using the revised Standard models that include aerosol and solar forcing mechanisms with all possible time lags but not by the Standard model when restricted to a zero time lag in aerosol and solar ozone forcings. As for Dobson Umkehr ozone measurements at Arosa, the aerosol effects are most significant in layers 8, 7, and 6 with no time lag, as is to be expected due to the optical contamination of Umkehr measurements by SAOD. The QBO and solar UV effects appear in all layers 4-8, and in total ozone. In order to account for annual modulation of the equatorial winds that affects ozone at midlatitudes, a new QBO proxy is selected and applied to the Dobson Umkehr measurements at Arosa. The QBO proxy turns out to be more effective to filter the modulated ozone signals at midlatitudes than the mostly used QBO proxy, the Singapore winds at 30 mb. A statistically significant negative phase relationship is found between solar UV variation and ozone response, especially in layer 4, implying dynamical effects of solar variations on ozone at midlatitudes. Linear negative trends in ozone of -7.8 +/- 1.1 and -5.2 +/- 1.4 [%/decade +/- 2σ] are calculated in layers 7 (~35 km) and 8 (~40 km), respectively, for the period of 1979-1996, with smaller trends of -2.2 +/- 1.0, 1.8 +/- 0.9, and -1.4 +/- 1.1 in layers 6 (~30 km), 5 (~25 km), and 4 (~20 km), respectively. A trend in total ozone (layers 1 through 10) of -2.9 +/- 1.2 [%/decade +/- 2σ] is found over this same period. The aerosol effects obtained from the TOMS zonal means become significant at midlatitudes. QBO ozone contributes to the TOMS zonal means by +/-2 to 4% of their means. The negative solar ozone responses are also found at midlatitudes from the TOMS measurements. The most negative trends from TOMS zonal means are about -6.3 +/- 0.6%/decade at 40-50°N.

On the role of tropopause folds in summertime tropospheric ozone over the eastern Mediterranean and the Middle East

NASA Astrophysics Data System (ADS)

Akritidis, Dimitris; Pozzer, Andrea; Zanis, Prodromos; Tyrlis, Evangelos; Škerlak, Bojan; Sprenger, Michael; Lelieveld, Jos

2016-11-01

We study the contribution of tropopause folds in the summertime pool of tropospheric ozone over the eastern Mediterranean and the Middle East (EMME) with the aid of the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. Tropopause fold events in EMAC simulations were identified with a 3-D labeling algorithm that detects folds at grid points where multiple crossings of the dynamical tropopause are computed. Subsequently the events featuring the largest horizontal and vertical extent were selected for further study. For the selection of these events we identified a significant contribution of the stratospheric ozone reservoir to the high concentrations of ozone in the middle and lower free troposphere over the EMME. A distinct increase of ozone is found over the EMME in the middle troposphere during summer as a result of the fold activity, shifting towards the southeast and decreasing altitude. We find that the interannual variability of near-surface ozone over the eastern Mediterranean (EM) during summer is related to that of both tropopause folds and ozone in the free troposphere.

Ozone budgets from the Dynamics and Chemistry of Marine Stratocumulus experiment

NASA Technical Reports Server (NTRS)

Kawa, S. R.; Pearson, R., Jr.

1989-01-01

Measurements from the Dynamics and Chemistry of marine Stratocumulus experiment have been used to study components of the regional ozone budget. The surface destruction rate is determined by eddy correlation of ozone and vertical velocity measured by a low-flying aircraft. Significant variability is found in the measured surface resistance; it is partially correlated with friction velocity but appears to have other controlling influences as well. The mean resistance is 4190 s/m which is higher (slower destruction) than most previous estimates for seawater. Flux and mean measurements throughout the marine boundary layer are used to estimate the net rate of in situ photochemical production/destruction of ozone. Averaged over the flights, ozone concentration is found to be near steady state, and a net of photochemical destruction of 0.02-0.07 ng/cu m per sec is diagnosed. This is an important confirmation of photochemical model results for the remote marine boundary layer. Ozone vertical distributions above the boundary layer show a strongly layered structure with very sharp gradients. These distributions are possibly related to the stratospheric ozone source.

Preliminary assessment of possible aerosol contamination effects on SAGE ozone trends in the lower stratosphere

NASA Technical Reports Server (NTRS)

Cunnold, Derek M.; Veiga, Robert E.

1991-01-01

An investigation of the validity of long-term ozone trends in the lower stratosphere derived from SAGE I and II measurements is described. At altitudes below approximately 20 km, it is important to separate the ozone and aerosol contributions to SAGE extinction at 600 nm. The correlation between SAGE II measurements of ozone and aerosols indicates that most of the variability in these parameters is associated with physically induced variations resulting from quasi-horizontal motions of air parcels. The SAGE ozone measurements are however found to be as much as 20 percent larger than coincident ozonesonde measurements between 15 and 20 km altitude. A sudden change in the difference at approximately 14.5 km altitude for which there is a change in the SAGE aerosol retrieval procedure suggests that SAGE ozone trends below 20 km altitude may be more sensitive to aerosol variations. Between 20 and 25 km altitude, however, both SAGE and the ozonesondes indicate a reduction in ozone of approximately 0.5 percent/year over the period 1979 to 1989 at midlatitudes of the Northern Hemisphere.

Particle Events as a Possible Source of Large Ozone Loss during Magnetic Polarity Transitions

NASA Technical Reports Server (NTRS)

vonKoenig, M.; Burrows, J. P.; Chipperfield, M. P.; Jackman, C. H.; Kallenrode, M.-B.; Kuenzi, K. F.; Quack, M.

2002-01-01

The energy deposition in the mesosphere and stratosphere during large extraterrestrial charged particle precipitation events has been known for some time to contribute to ozone losses due to the formation of potential ozone destroying species like NO(sub x), and HO(sub x). These impacts have been measured and can be reproduced with chemistry models fairly well. In the recent past, however, even the impact of the largest solar proton events on the total amount of ozone has been small compared to the dynamical variability of ozone, and to the anthropogenic induced impacts like the Antarctic 'ozone hole'. This is due to the shielding effect of the magnetic field. However, there is evidence that the earth's magnetic field may approach a reversal. This could lead to a decrease of magnetic field strength to less than 25% of its usual value over a period of several centuries . We show that with realistic estimates of very large solar proton events, scenarios similar to the Antarctic ozone hole of the 1990s may occur during a magnetic polarity transition.

Tropospheric Ozone Over North America

NASA Astrophysics Data System (ADS)

Oltmans, S. J.; Thompson, A. M.; Cooper, O. R.; Merrill, J. T.; Tarasick, D. W.; Newchurch, M. J.

2007-05-01

Ozone in the troposphere plays a significant role as an absorber of infrared radiation (greenhouse gas), in the cleansing capacity of the atmosphere as a precursor of hydroxol radical formation, and a regulated air pollutant capable of deleterious health and ecosystem effects. Knowledge of the ozone budget in the troposphere over North America (NA) is required to properly understand the various mechanisms that contribute to the measured distribution and to develop and test models capable of simulating and predicting this key player in atmospheric chemical and physical processes. Recent field campaigns including the 2004 and 2006 INTEX Ozone Network Studies (IONS) http:croc.gsfc.nasa.gov/intexb/ions06.html that have included intensive ozone profile measurements from ozonesondes provide a unique data set for describing tropospheric ozone over a significant portion of the North American continent. These campaigns have focused on the spring and summer seasons when tropospheric ozone over NA is particularly influenced by long-range transport processes, significant photochemical ozone production resulting from both anthropogenic and natural (lightning) precursor emissions, and exchange with the stratosphere. This study uses ozone profiles measured over NA in the latitude band from approximately 12-60N, extending from the tropics to the high mid latitudes, to describe the seasonal behavior of tropospheric ozone over NA with an emphasis on the spring and summer. This includes the variability within seasons at a particular site as well as the contrasts between the seasons. Emphasis is placed on the variations among the sites including latitudinal and longitudinal gradients and how these differ through the seasons and with altitude in the troposphere. Regional differences are most pronounced during the summer season likely reflecting the influence of a wider variation in processes influencing the tropospheric ozone distribution including lightning NOX production in the upper troposphere and active photochemistry from human emitted precursors in the lower troposphere. In all seasons, including the summer, transfer from the stratosphere significantly influences the upper tropospheric distribution at mid latitude (35-55N) locations. Although the seasonal maximum is found in spring in most locations and throughout much of the troposphere, this season tends to show less geographic variability compared to the summer. The FLEXPART Lagrangian tracer model is used to help identify processes associated with distinctive profile characteristics in the ozonesonde measurements.

Effect of tropospheric ozone on morphological characteristics of Nicotiana tabacum L., Phaseolus vulgaris L. and Petunia×Hybrida L. in ambient air conditions.

PubMed

Borowiak, Klaudia; Wujeska, Agnieszka

2012-03-01

The cumulative ozone effect on morphological parameters (visible leaf injury, plant height and leaf growth, number of bean pods, petunia flowers and stalks) was examined in this study. Well-known ozonesensitive (Bel W3) and ozone-resistant (Bel B) tobacco cultivars as well as bean cv. Nerina and petunia cv. White cascade, both recognized as ozone sensitive, were used in the experiment. Investigations were carried out at two exposure sites varying in tropospheric ozone levels. Ozone negatively affected the leaf growth of both tobacco cultivars and bean. A negative relation was also found for ozone concentration and tobacco plant height. Number of petunia flowers and stalks and bean pods was positively correlated with ozone concentration. This could have been connected with earlier plant maturation due to faster generative development of plants in ozone-stress conditions.

Contrasting subtropical PV intrusion frequency and their impact on tropospheric Ozone distribution over Pacific Ocean in El-Niño and La-Niña conditions.

PubMed

Nath, Debashis; Chen, Wen; Graf, Hans-F; Lan, Xiaoqiang; Gong, Hainan

2017-09-20

Upper tropospheric equatorial westerly ducts over the Pacific Ocean are the preferred location for Rossby wave breaking events during boreal winter and spring. These subtropical wave breaking events lead to the intrusion of high PV (potential vorticity) air along the extra-tropical tropopause and transport ozone rich dry stratospheric air into the tropics. The intrusion frequency has strong interannual variability due to ENSO (El-Niño/Southern Oscillation), with more events under La-Niña and less under El-Niño conditions. This may result from stronger equatorial westerly ducts and subtropical jets during La-Niña and weaker during El-Niño. It was previously suggested that the interannual variability of the tropospheric ozone distribution over the central-eastern Pacific Ocean is mainly driven by convective activity related to ENSO and that the barotropic nature of the subtropical intrusions restricts the tracers within the UT. However, our analysis shows that tropospheric ozone concentration and subtropical intrusions account ~65% of the co- variability (below 5 km) in the outer tropical (10-25°N) central Pacific Ocean, particularly during La-Niña conditions. Additionally, we find a two-fold increase and westward shift in the intrusion frequency over the Pacific Ocean, due to the climate regime shift in SST pattern during 1997/98.

Ozone and sulfur dioxide effects on three tall fescue cultivars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flagler, R.B.; Youngner, V.B.

Although many reports have been published concerning differential susceptibility of various crops and/or cultivars to air pollutants, most have used foliar injury instead of the marketable yield as the factor that determined susceptibility for the crop. In an examination of screening in terms of marketable yield, three cultivars of tall fescue (Festuca arundinacea Schreb.), 'Alta,' 'Fawn,' and 'Kentucky 31,' were exposed to 0-0.40 ppm O/sub 3/ or 0-0.50 ppm SO/sub 2/ 6 h/d, once a week, for 7 and 9 weeks, respectively. Experimental design was a randomized complete block with three replications. Statistical analysis was by standard analysis of variancemore » and regression techniques. Three variables were analyzed: top dry weight (yield), tiller number, and weight per tiller. Ozone had a significant effect on all three variables. Significant linear decreases in yield and weight per tiller occurred with increasing O/sub 3/ concentrations. Linear regressions of these variables on O/sub 3/ concentration produced significantly different regression coefficients. The coefficient for Kentucky 31 was significantly greater than Alta or Fawn, which did not differ from each other. This indicated that Kentucky 31 was more susceptible to O/sub 3/ than either of the other cultivars. Percent reductions in dry weight for the three cultivars at highest O/sub 3/ level were 35, 44, and 53%, respectively, for Fawn, Alta, and Kentucky 31. For weight per tiller, Kentucky 31 had a higher percent reduction than the other cultivars (59 vs. 46 and 44%). Tiller number was generally increased by O/sub 3/, but this variable was not useful for determining differential susceptibility to the pollutant. Sulfur dioxide treatments produced no significant effects on any of the variables analyzed.« less

Sensitive subgroups and normal variation in pulmonary function response to air pollution episodes.

PubMed Central

Brunekreef, B; Kinney, P L; Ware, J H; Dockery, D; Speizer, F E; Spengler, J D; Ferris, B G

1991-01-01

The Clean Air Act requires that sensitive subgroups of exposed populations be protected from adverse health effects of air pollution exposure. Hence, data suggesting the existence of sensitive subgroups can have an important impact on regulatory decisions. Some investigators have interpreted differences among individuals in observed pulmonary function response to air pollution episodes as evidence that individuals differ in their sensitivity. An alternative explanation is that the differences are due entirely to normal variation in repeated pulmonary function measurements. This paper investigates this question by reanalyzing data from three studies of children exposed to air pollution episodes to determine whether the observed variability in pulmonary function response indicates differences in sensitivity or natural interoccasion variability. One study investigated exposures to total suspended particulates (TSP), the other two investigated exposure to ozone. In all studies, each child's response to air pollution exposures was summarized by regressing that child's set of pulmonary function measurements on the air pollution concentrations on the day or days before measurement. The within-child and between-child variances of these slopes were used to test the hypothesis of variable sensitivity. Regression slopes did not vary significantly among children exposed to episodes of high TSP concentration, but there was evidence of heterogeneity in both studies of ozone exposures. The finding of heterogeneous response to ozone exposure is consistent with the epidemiologic and chamber studies of ozone exposures, but the lack of evidence for heterogeneous response to TSP exposures implies that observed variation in response can be explained by sampling variability rather than the presence of sensitive subgroup. PMID:2050060

Mechanisms for the extratropical QBO in circulation and ozone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinnersley, J.S.; Tung, K.K.

1999-06-15

A two-and-a-half-dimensional interactive stratospheric model, whose equatorial zonal wind was relaxed toward the observed Singapore zonal wind, was able to reproduce much of the observed quasi-biennial oscillation (QBO) variability in the column ozone, in its vertical distribution in the low and middle latitudes, and also in the high southern polar latitudes. To reveal the mechanisms responsible for producing the modeled QBO signal over the globe, several control runs were also performed. The authors find that the ozone variability in the lower stratosphere--and hence also in the column--is determined mainly by two dynamical mechanisms. In the low to midlatitudes it ismore » created by a direct QBO circulation. Unlike the classic picture of a nonseasonal two-cell QBO circulation symmetric about the equator, a more correct picture is a direct QBO circulation that is strongly seasonal, driven by the seasonality in diabatic heating, which is very weak in the summer hemisphere and strong in the winter hemisphere at low and midlatitudes. Transport by the climatological circulation and diffusion is found to be ineffective. At high latitudes, there is again a circulation anomaly, but here it is induced by the modulation of the planetary wave potential vorticity flux by the QBO. This so-called Holton-Tan mechanism is responsible for most of the QBO ozone signal poleward of 60[degree]. During spring in the modeled northern polar region, chaotic behavior is another important source of interannual variability, in addition to the interannual variability of planetary wave sources in the troposphere previously studied by the authors.« less

Variability of Ozone, OX and NOx in Rural and Urban Areas in Marmara Region of Turkey

NASA Astrophysics Data System (ADS)

Kasparoǧlu, Sabin; İncecik, Selahattin; Topçu, H. Sema

2017-04-01

Marmara region is located in northwest of Turkey and it is bordered by Greece and the Aegean Sea to the west, and Bulgaria, the Black Sea to the north covers about 11,000 km2. Sea of Marmara is located at the center of the region. The region has the largest population in Turkey with about 23 million inhabitants. It is Turkey's main industrial region and It is the territory which is provided by a quarter of the Turkish economy. Moreover, the region is economically the most developed area of Turkey. Its agricultural potential is very rich. For example, about 73% of the sunflower production and 30 % of corn production of Turkey is done in this region. The aim of the study is to assess the spatial and temporal variations in O3, NO, and NO2 in Marmara region of Turkey based on the analysis of hourly concentrations collected at 22 monitoring stations (7 rural and 15 urban) over three years (2013-2016). This is the first study in the region. In this way possible reasons of the results will be useful in the design of control strategies for photochemical pollution in this region. For this purpose, diurnal variations of NOx, O3 and OX were examined for rural and urban sites. The total levels of oxidant (OX) which are considered to be sum of O3 and NO2 were determined. In rural sites, NOx concentrations are generally lower than at urban and polluted sites of Marmara region. We found that usually O3 peak time in rural areas are occurred at around 15:00 LST while mean peak values vary between 70-85 µg/m3. The highest mean concentrations of NO were also observed at 09:00 LST around 35-50 µg/m3 in rural areas while varies at the highest at around 75-85 µg/m3 in polluted sites. Due to the NOx -dependent contribution corresponds to local production of ozone and the NOx -independent contribution corresponds to regional concentrations, we examined OX versus NOx for daytime (10:00-18:00LST) and nighttime (19:00-09:00LST)periods to understand the contaminants of NOx from local sources or regional contribution in the region. We found that total OX appears to increase linearly with NOx in rural sites. Moreover, 3-day isentropic HYSPLIT back-trajectory analysis ending at 500m agl for ozone season are analyzed for the ozone season (1st May to 30th September). In the presented study, the prevailing mesoscale meteorological conditions occurring during ozone season over the Marmara region are examined from the reanalysis data of NOAA ESRL. Finally, AOT40 index under EU ozone Directive are examined for vegetation and forest areas in Marmara region.

Impact of HVAC filter on indoor air quality in terms of ozone removal and carbonyls generation

NASA Astrophysics Data System (ADS)

Lin, Chi-Chi; Chen, Hsuan-Yu

2014-06-01

This study aims at detecting ozone removal rates and corresponding carbonyls generated by ozone reaction with HVAC filters from various building, i.e., shopping mall, school, and office building. Studies were conducted in a small-scale environmental chamber. By examining dust properties including organic carbon proportion and specific surface area of dusts adsorbed on filters along with ozone removal rates and carbonyls generation rate, the relationship among dust properties, ozone removal rates, and carbonyls generation was identified. The results indicate a well-defined positive correlation between ozone removal efficiency and carbonyls generation on filters, as well as a positive correlation among the mass of organic carbon on filters, ozone removal efficiency and carbonyls generations.

A Lagrangian analysis of mid-latitude stratospheric ozone variability and long-term trends.

NASA Astrophysics Data System (ADS)

Koch, G.; Wernli, H.; Staehelin, J.; Peter, T.

2002-05-01

A systematic Lagrangian investigation is performed of wintertime high-resolution stratospheric ozone soundings at Payerne, Switzerland, from January 1970 to March 2001. For every ozone sounding, 10-day backward trajectories have been calculated on 16 isentropic levels using NCEP reanalysis data. Both the minimum/maximum latitude and potential vorticity (PV) averaged along the trajectories are used as indicators of the air parcels' ``origin''. The importance of transport for the understandin g of single ozone profiles is confirmed by a statistical analysis which shows that negative/positive ozone deviations gener ally coincide with transport from regions with climatologically low/high ozone values. The stable relationship between PV and ozone for the 32 year period indicates either no direct chemical impact or no temporal change of this impact. In the upper layer the PV-ozone relationship changes significantly after 1987 and a separate trend analysis for air masses transported from the polar, midlatitude and subtropical regions shows negative ozone trends in all three categories (with a maximum for the polar region). This is not direct evidence for, but would be in agreement with, an increased chemical ozone depletion in the Arctic since the late 1980s. The reasons for the negative trend in the mid-stratospheric air masses with subtropical origin that are in qualitative agreement with recent satellite observations are presently unknown.

Quantifying Uncertainty in Projections of Stratospheric Ozone Over the 21st Century

NASA Technical Reports Server (NTRS)

Charlton-Perez, A. J.; Hawkins, E.; Eyring, V.; Cionni, I.; Bodeker, G. E.; Kinnison, D. E.; Akiyoshi, H.; Frith, S. M.; Garcia, R.; Gettelman, A.;

Spatial distribution of tropospheric ozone in national parks of California: interpretation of passive-sampler data.

PubMed

Ray, J D

2001-09-28

The National Park Service (NPS) has tested and used passive ozone samplers for several years to get baseline values for parks and to determine the spatial variability within parks. Experience has shown that the Ogawa passive samplers can provide +/-10% accuracy when used with a quality assurance program consisting of blanks, duplicates, collocated instrumentation, and a standard operating procedure that carefully guides site operators. Although the passive device does not meet EPA criteria as a certified method (mainly, that hourly values be measured), it does provide seasonal summed values of ozone. The seasonal ozone concentrations from the passive devices can be compared to other monitoring to determine baseline values, trends, and spatial variations. This point is illustrated with some kriged interpolation maps of ozone statistics. Passive ozone samplers were used to get elevational gradients and spatial distributions of ozone within a park. This was done in varying degrees at Mount Rainier, Olympic, Sequoia-Kings Canyon, Yosemite, Joshua Tree, Rocky Mountain, and Great Smoky Mountains national parks. The ozone has been found to vary by factors of 2 and 3 within a park when average ozone is compared between locations. Specific examples of the spatial distributions of ozone in three parks within California are given using interpolation maps. Positive aspects and limitations of the passive sampling approach are presented.

Estimation of ozone dry deposition over Europe for the period 2071-2100

NASA Astrophysics Data System (ADS)

Komjáthy, Eszter; Gelybó, Györgyi; László Lagzi, István.; Mészáros, Róbert

2010-05-01

Ozone in the lower troposphere is a phytotoxic air pollutant which can cause injury to plant tissues, causing reduction in plant growth and productivity. In the last decades, several investigations have been carried out for the purpose to estimate ozone load over different surface types. At the same time, the changes of atmospheric variables as well as surface/vegetation parameters due to the global climate change could also strongly modify both temporal and spatial variations of ozone load over Europe. In this study, the possible effects of climate change on ozone deposition are analyzed. Using a sophisticated deposition model, ozone deposition was estimated on a regular grid over Europe for the period 2071-2100. Our aim is to determine the uncertainties and the possible degree of change in ozone deposition velocity as an important predictor of total ozone load using climate data from multiple climate models and runs. For these model calculations, results of the PRUDENCE (Predicting of Regional Scenarios and Uncertainties for Defining European Climate Change Risks and Effects) climate prediction project were used. As a first step, seasonal variations of ozone deposition over different vegetation types in case of different climate scenarios are presented in this study. Besides model calculations, in the frame of a sensitivity analyses, the effects of surface/vegetation parameters (e.g. leaf area index or stomatal resistance) on ozone deposition under a modified climate regime have also been analyzed.

Key drivers of ozone change and its radiative forcing over the 21st century

NASA Astrophysics Data System (ADS)

Iglesias-Suarez, Fernando; Kinnison, Douglas E.; Rap, Alexandru; Maycock, Amanda C.; Wild, Oliver; Young, Paul J.

2018-05-01

Over the 21st century changes in both tropospheric and stratospheric ozone are likely to have important consequences for the Earth's radiative balance. In this study, we investigate the radiative forcing from future ozone changes using the Community Earth System Model (CESM1), with the Whole Atmosphere Community Climate Model (WACCM), and including fully coupled radiation and chemistry schemes. Using year 2100 conditions from the Representative Concentration Pathway 8.5 (RCP8.5) scenario, we quantify the individual contributions to ozone radiative forcing of (1) climate change, (2) reduced concentrations of ozone depleting substances (ODSs), and (3) methane increases. We calculate future ozone radiative forcings and their standard error (SE; associated with inter-annual variability of ozone) relative to year 2000 of (1) 33 ± 104 m Wm-2, (2) 163 ± 109 m Wm-2, and (3) 238 ± 113 m Wm-2 due to climate change, ODSs, and methane, respectively. Our best estimate of net ozone forcing in this set of simulations is 430 ± 130 m Wm-2 relative to year 2000 and 760 ± 230 m Wm-2 relative to year 1750, with the 95 % confidence interval given by ±30 %. We find that the overall long-term tropospheric ozone forcing from methane chemistry-climate feedbacks related to OH and methane lifetime is relatively small (46 m Wm-2). Ozone radiative forcing associated with climate change and stratospheric ozone recovery are robust with regard to background climate conditions, even though the ozone response is sensitive to both changes in atmospheric composition and climate. Changes in stratospheric-produced ozone account for ˜ 50 % of the overall radiative forcing for the 2000-2100 period in this set of simulations, highlighting the key role of the stratosphere in determining future ozone radiative forcing.

Tropospheric Ozone Over a Tropical Atlantic Station in the Northern Hemisphere: Paramaribo, Surinam (6 deg N, 55 deg W)

NASA Technical Reports Server (NTRS)

Peters, W.; Krol, M. C.; Fortuin, J. P. F.; Kelder, H. M.; Thompson, A. M.; Becker, C. R.; Lelieveld, J.; Crutzen, P. J.

2003-01-01

We present an analysis of 2.5 years of weekly ozone soundings conducted at a new monitoring station in Paramaribo, Surinam (6 deg N,55 deg W). This is currently one of only three ozone sounding stations in the northern hemisphere (NH) tropics, and the only one in the equatorial Atlantic region. Paramaribo is part of the Southern Hemisphere ADditional Ozone Sounding program (SHADOZ). Due to its position close to the equator, the Inter Tropical Convergence Zone (ITCZ) passes over Paramaribo twice per year, which results in a semi-annual seasonality of many parameters including relative humidity and ozone. The dataset from Paramaribo is used to: (1) evaluate ozone variability relative to precipitation, atmospheric circulation patterns and biomass burning; (2) contrast ozone at the NH equatorial Atlantic with that at nearby southern hemisphere (SH) stations Natal (6 deg S,35 deg W) and Ascension (8 deg S,14 deg W); (3) compare the seasonality of tropospheric ozone with a satellite-derived ozone product: Tropical Tropospheric Ozone Columns from the Modified Residual method (MR-TTOC). We find that Paramaribo is a distinctly Atlantic station. Despite its position north of the equator, it resembles nearby SH stations during most of the year. Transport patterns in the lower and middle troposphere during February and March differ from SH stations, which leads to a seasonality of ozone with two maxima. MR-TTOC over Paramaribo does not match the observed seasonality of ozone due to the use of a SH ozone sonde climatology in the MR method. The Paramaribo ozone record is used to suggest an improvement for northern hemisphere MR-TTOC retrievals. We conclude that station Paramaribo shows unique features in the region, and clearly adds new information to the existing SHADOZ record.

Geostatistics as a validation tool for setting ozone standards for durum wheat.

PubMed

De Marco, Alessandra; Screpanti, Augusto; Paoletti, Elena

2010-02-01

Which is the best standard for protecting plants from ozone? To answer this question, we must validate the standards by testing biological responses vs. ambient data in the field. A validation is missing for European and USA standards, because the networks for ozone, meteorology and plant responses are spatially independent. We proposed geostatistics as validation tool, and used durum wheat in central Italy as a test. The standards summarized ozone impact on yield better than hourly averages. Although USA criteria explained ozone-induced yield losses better than European criteria, USA legal level (75 ppb) protected only 39% of sites. European exposure-based standards protected > or =90%. Reducing the USA level to the Canadian 65 ppb or using W126 protected 91% and 97%, respectively. For a no-threshold accumulated stomatal flux, 22 mmol m(-2) was suggested to protect 97% of sites. In a multiple regression, precipitation explained 22% and ozone explained <0.9% of yield variability. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

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

Trends of rural tropospheric ozone at the northwest of the Iberian Peninsula.

PubMed

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 NO(x) 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.

Vitamin D Synthesis by UV Radiation: the Importance of Ozone Monitoring

NASA Astrophysics Data System (ADS)

Olds, W. J.; Moore, M. R.; Kimlin, M. G.

2006-12-01

The majority of humans rely on incidental sun exposure to maintain vitamin D sufficiency. Depending on where thresholds of vitamin D "sufficiency" are defined, it was recently stated that up to one billion people worldwide have suboptimal vitamin D levels (Bouillon, R., University of Leuven). Even in sunny southeast Queensland, the world's skin cancer capital, a 2006 study uncovered deficiency rates of up to 78% (at a threshold of 75 nmol/L of circulating 25-hydroxyvitamin D). Vitamin D regulates calcium absorption and inadequate levels are proven to result in osteomalacia, osteoporosis, rickets, bone pain and general skeletal weakness. Recent evidence also suggests vitamin D plays a preventative role in autoimmune diseases including numerous cancers, diabetes, schizophrenia, coronary heart disease, depression and other disorders. The most promising means of alleviating the worldwide burden of vitamin D deficiency seems to be by increased UV exposure. However, a much more mature understanding of UV exposures encountered in everyday life is required. This understanding is fundamentally founded in geophysics. UV exposures are strongly influenced by season/time of year, time of day, climate, location, pollution, aerosols and, importantly, ozone. In this work, we use computer simulations to obtain daily totals of vitamin D producing UV at numerous latitudes during one year. The ozone concentration is varied from 260 DU to 360 DU to determine the role of ozone variability on the ambient levels of vitamin D UV. Vitamin D synthesis is highly dependent on UVB. In our results, we demonstrate that this has important implications. Namely, vitamin D is strongly affected by ozone variability, since ozone filters UVB more strongly than UVA. Moreover, since erythema (sunburn) can occur at UVA wavelengths, ozone variation will more strongly affect vitamin D synthesis than erythema. Our results highlight that ozone monitoring is essential for understanding appropriate UV exposures for vitamin D health. We finally discuss implications for population health and how geophysics continues to play a vital role in addressing the widespread dilemma of vitamin D deficiency.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, L.; Hill, W.J.

A method is proposed to estimate the effect of long-term variations in total ozone on the error incurred in determining a trend in total ozone due to man-made effects. When this method is applied to data from Arosa, Switzerland over the years 1932--1980, a component of the standard error of the trend estimate equal to 0.6 percent per decade is obtained. If this estimate of long-term trend variability at Arosa is not too different from global long-term trend variability, then the threshold ( +- 2 standard errors) for detecting an ozone trend in the 1970's that is outside of whatmore » could be expected from natural variation alone and hence be man-made would range from 1.35% (Reinsel et al, 1981) to 1.8%. The latter value is obtained by combining the Reinsel et al result with the result here, assuming that the error variations that both studies measure are independent and additive. Estimates for long-term trend variation over other time periods are also derived. Simulations that measure the precision of the estimate of long-term variability are reported.« less

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

Solar forcing for CMIP6 (v3.2)

NASA Astrophysics Data System (ADS)

Matthes, Katja; Funke, Bernd; Andersson, Monika E.; Barnard, Luke; Beer, Jürg; Charbonneau, Paul; Clilverd, Mark A.; Dudok de Wit, Thierry; Haberreiter, Margit; Hendry, Aaron; Jackman, Charles H.; Kretzschmar, Matthieu; Kruschke, Tim; Kunze, Markus; Langematz, Ulrike; Marsh, Daniel R.; Maycock, Amanda C.; Misios, Stergios; Rodger, Craig J.; Scaife, Adam A.; Seppälä, Annika; Shangguan, Ming; Sinnhuber, Miriam; Tourpali, Kleareti; Usoskin, Ilya; van de Kamp, Max; Verronen, Pekka T.; Versick, Stefan

2017-06-01

This paper describes the recommended solar forcing dataset for CMIP6 and highlights changes with respect to CMIP5. The solar forcing is provided for radiative properties, namely total solar irradiance (TSI), solar spectral irradiance (SSI), and the F10.7 index as well as particle forcing, including geomagnetic indices Ap and Kp, and ionization rates to account for effects of solar protons, electrons, and galactic cosmic rays. This is the first time that a recommendation for solar-driven particle forcing has been provided for a CMIP exercise. The solar forcing datasets are provided at daily and monthly resolution separately for the CMIP6 preindustrial control, historical (1850-2014), and future (2015-2300) simulations. For the preindustrial control simulation, both constant and time-varying solar forcing components are provided, with the latter including variability on 11-year and shorter timescales but no long-term changes. For the future, we provide a realistic scenario of what solar behavior could be, as well as an additional extreme Maunder-minimum-like sensitivity scenario. This paper describes the forcing datasets and also provides detailed recommendations as to their implementation in current climate models.For the historical simulations, the TSI and SSI time series are defined as the average of two solar irradiance models that are adapted to CMIP6 needs: an empirical one (NRLTSI2-NRLSSI2) and a semi-empirical one (SATIRE). A new and lower TSI value is recommended: the contemporary solar-cycle average is now 1361.0 W m-2. The slight negative trend in TSI over the three most recent solar cycles in the CMIP6 dataset leads to only a small global radiative forcing of -0.04 W m-2. In the 200-400 nm wavelength range, which is important for ozone photochemistry, the CMIP6 solar forcing dataset shows a larger solar-cycle variability contribution to TSI than in CMIP5 (50 % compared to 35 %).We compare the climatic effects of the CMIP6 solar forcing dataset to its CMIP5 predecessor by using time-slice experiments of two chemistry-climate models and a reference radiative transfer model. The differences in the long-term mean SSI in the CMIP6 dataset, compared to CMIP5, impact on climatological stratospheric conditions (lower shortwave heating rates of -0.35 K day-1 at the stratopause), cooler stratospheric temperatures (-1.5 K in the upper stratosphere), lower ozone abundances in the lower stratosphere (-3 %), and higher ozone abundances (+1.5 % in the upper stratosphere and lower mesosphere). Between the maximum and minimum phases of the 11-year solar cycle, there is an increase in shortwave heating rates (+0.2 K day-1 at the stratopause), temperatures ( ˜ 1 K at the stratopause), and ozone (+2.5 % in the upper stratosphere) in the tropical upper stratosphere using the CMIP6 forcing dataset. This solar-cycle response is slightly larger, but not statistically significantly different from that for the CMIP5 forcing dataset.CMIP6 models with a well-resolved shortwave radiation scheme are encouraged to prescribe SSI changes and include solar-induced stratospheric ozone variations, in order to better represent solar climate variability compared to models that only prescribe TSI and/or exclude the solar-ozone response. We show that monthly-mean solar-induced ozone variations are implicitly included in the SPARC/CCMI CMIP6 Ozone Database for historical simulations, which is derived from transient chemistry-climate model simulations and has been developed for climate models that do not calculate ozone interactively. CMIP6 models without chemistry that perform a preindustrial control simulation with time-varying solar forcing will need to use a modified version of the SPARC/CCMI Ozone Database that includes solar variability. CMIP6 models with interactive chemistry are also encouraged to use the particle forcing datasets, which will allow the potential long-term effects of particles to be addressed for the first time. The consideration of particle forcing has been shown to significantly improve the representation of reactive nitrogen and ozone variability in the polar middle atmosphere, eventually resulting in further improvements in the representation of solar climate variability in global models.

Variable performance of outbreak defoliators on aspen clones exposed to elevated CO2 and O3

Treesearch

Daniel A. Herms; William J. Mattson; David N. Karowe; Mark D. Coleman; Terry M. Trier; Bruce A. Birr; J. G. Isebrands

1996-01-01

Increasing atmospheric concentrations of ozone and CO2 affect many aspects of tree physiology. However, their effects on tree resistance to insects have received relatively little attention. The objectives of this study were to test the effects of elevated CO2 and ozone on the resistance of three quaking aspen (...

Surface ozone in the Lake Tahoe Basin

Treesearch

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

2015-01-01

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...

Variability of Stratospheric Reactive Nitrogen and Ozone Related to the QBO

NASA Astrophysics Data System (ADS)

Park, M.; Randel, W. J.; Kinnison, D. E.; Bourassa, A. E.; Degenstein, D. A.; Roth, C. Z.; McLinden, C. A.; Sioris, C. E.; Livesey, N. J.; Santee, M. L.

2017-09-01

The stratospheric quasi-biennial oscillation (QBO) dominates interannual variability of dynamical variables and trace constituents in the tropical stratosphere and provides a natural experiment to test circulation-chemistry interactions. This work quantifies the relationships among ozone (O3), reactive nitrogen (NOy), and source gas N2O, and their links to the QBO, based on satellite constituent measurements and meteorological data spanning 2005-2014 (over four QBO cycles). Data include O3, HNO3, and N2O from the Aura Microwave Limb Sounder and an NOx proxy derived from Optical Spectrograph and Infrared Imager System NO2 measurements combined with a photochemical box model (= NOx*). Results are compared to simulations from the Whole Atmosphere Community Climate Model, version 4 incorporating a QBO circulation nudged to assimilated winds. Cross correlations and composites with respect to the QBO phase show coherent 180° out-of-phase relationships between NOy and N2O throughout the stratosphere, with the NOx/HNO3 ratio increasing with altitude. The anomalies in NOy species propagate coherently downward with the QBO. Ozone is anticorrelated with reactive nitrogen in the middle stratosphere above 28 km due to NOx control of ozone catalytic loss cycles. Quantitative comparisons of nitrogen partitioning and O3 sensitivity to NOx show good overall agreement between satellite observations and model results (suggesting closure of the NOy budget), although the model results show larger (up to 20%) N2O, NOx, and O3 variations near 35 km compared to observations. These analyses serve to assess the consistency of diverse satellite-based data sets and also to evaluate nitrogen partitioning and NOx-dependent ozone chemistry in the global model.

Overview for the reanalysis of Mariner 9 UV spectrometer data for ozone, cloud, and dust abundances, and their interaction over climate timescales

NASA Technical Reports Server (NTRS)

Lindner, Bernhard Lee

1992-01-01

Mariner 9 UV spectrometer data were reinverted for the ozone abundance, cloud abundance, dust abundance, and polar-cap albedo. The original reduction of the spectra ignored the presence of atmospheric dust and clouds, even though their abundance is substantial and can mask appreciable amounts of ozone if not accounted for (Lindner, 1988). The Mariner 9 ozone data has been used as a benchmark in all theoretical models of atmospheric composition, escape, and photochemistry. A second objective is to examine the data for the interrelationship of the ozone cycle, dust cycle, and cloud cycle, on an annual, inter-annual, and climatic basis, testing predictions by Lindner (1988). This also has implications for many terrestrial ozone studies, such as the ozone hole, acid rain, and ozone-smog. A third objective is to evaluate the efficacy of the reflectance spectroscopy technique at retrieving the ozone abundance on Mars. This would be useful for planning ozone observations on future Mars missions or the terrestrial troposphere.

Evaluation of emission control strategies to reduce ozone pollution in the Paso del Norte region using a photochemical air quality modeling system

NASA Astrophysics Data System (ADS)

Valenzuela, Victor Hugo

Air pollution emissions control strategies to reduce ozone precursor pollutants are analyzed by applying a photochemical modeling system. Simulations of air quality conditions during an ozone episode which occurred in June, 2006 are undertaken by increasing or reducing area source emissions in Ciudad Juarez, Chihuahua, Mexico. Two air pollutants are primary drivers in the formation of tropospheric ozone. Oxides of nitrogen (NOx) and volatile organic compounds (VOC) undergo multiple chemical reactions under favorable meteorological conditions to form ozone, which is a secondary pollutant that irritates respiratory systems in sensitive individuals especially the elderly and young children. The U.S. Environmental Protection Agency established National Ambient Air Quality Standards (NAAQS) to limit ambient air pollutants such as ozone by establishing an 8-hour average concentration of 0.075 ppm as the threshold at which a violation of the standard occurs. Ozone forms primarily due reactions in the troposphere of NOx and VOC emissions generated primarily by anthropogenic sources in urban regions. Data from emissions inventories indicate area sources account for ˜15 of NOx and ˜45% of regional VOC emissions. Area sources include gasoline stations, automotive paint bodyshops and nonroad mobile sources. Multiplicity of air pollution emissions sources provides an opportunity to investigate and potentially implement air quality improvement strategies to reduce emissions which contribute to elevated ozone concentrations. A baseline modeling scenario was established using the CAMx photochemical air quality model from which a series of sensitivity analyses for evaluating air quality control strategies were conducted. Modifications to area source emissions were made by varying NOx and / or VOC emissions in the areas of particular interest. Model performance was assessed for each sensitivity analysis. Normalized bias (NB) and normalized error (NE) were used to identify variability of the PREDICTED to OBSERVED ozone concentrations of both BASELINE model and simulations with modified emissions assessed by the sensitivity analysis. All simulations were found to vary within acceptable ranges of these two criteria variables. Simulation results indicate ozone formation in the PdN region is VOC-limited. Under VOC-limited conditions, modifications to NOx emissions do not produce a marked increase or decrease in ozone concentrations. Modifications to VOC emissions generated the highest variability in ozone concentrations. Increasing VOC emissions by 75% produced results which minimized model bias and error when comparing PREDICTED and OBSERVED ozone concentrations. Increasing VOC emissions by 75% either alone or in combination with a 75% increase in NOx emissions generated PREDICTED ozone concentrations very near to OBSERVED ozone. By evaluating the changes in ambient ozone concentrations through photochemical modeling, air quality planners may identify the most efficient or effective VOC emissions control strategies for area sources. Among the strategies to achieve emissions reductions are installation of gasoline vapor recovery systems, replacing high-pressure low-volume surface coating paint spray guns with high-volume low-pressure spray paint guns, requiring emissions control booths for surface coating operations as well as undertaking solvent management practices, requiring the sale of low VOC paint solvents in the surface-coating industry, and requiring low-VOC solvents in the dry cleaning industry. Other strategies to reduce VOC emissions include initiating Eco-Driving strategies to reduce fuel consumption from mobile sources and minimize vehicle idling at the international ports of entry by reducing bridge wait times. This dissertation depicts a tool for evaluating impacts of emissions on regional air quality by addressing the highly unresolved fugitive emissions in the Paso del Norte region. It provides a protocol for decision makers to assess the effects of various emission control strategies in the region. Impacts of specific source categories such as the international ports of entry, gasoline stations, paint body shops, truck stops, and military installations on the regional air quality can be easily and systematically addressed in a timely manner in the future.

Fate of return activated sludge after ozonation: an optimization study for sludge disintegration.

PubMed

Demir, Ozlem; Filibeli, Ayse

2012-09-01

The effects of ozonation on sludge disintegration should be investigated before the application of ozone during biological treatment, in order to minimize excess sludge production. In this study, changes in sludge and supernatant after ozonation of return activated sludge were investigated for seven different ozone doses. The optimum ozone dose to avoid inhibition of ozonation and high ozone cost was determined in terms of disintegration degree as 0.05 g O3/gTS. Suspended solid and volatile suspended solid concentrations of sludge decreased by 77.8% and 71.6%, respectively, at the optimum ozone dose. Ozonation significantly decomposed sludge flocs. The release of cell contents was proved by the increase of supernatant total nitrogen (TN) and phosphorus (TP). While TN increased from 7 mg/L to 151 mg/L, TP increased from 8.8 to 33 mg/L at the optimum ozone dose. The dewaterability and filterability characteristics of the ozonated sludge were also examined. Capillary suction time increased with increasing ozone dosage, but specific resistance to filtration increased to a specific value and then decreased dramatically. The particle size distribution changed significantly as a result of floc disruption at an optimum dose of 0.05 gO3/gTS.

Surface ozone in China: present-day distribution and long-term changes

NASA Astrophysics Data System (ADS)

Xu, X.; Lin, W.; Xu, W.

2017-12-01

Reliable knowledge of spatio-temporal variations of surface ozone is highly needed to assess the impacts of ozone on human health, ecosystem and climate. Although regional distributions and trends of surface ozone in European and North American countries have been well characterized, little is known about the variability of surface ozone in many other countries, including China, where emissions of ozone precursors have been changing rapidly in recent decades. Here we present the first comprehensive description of present-day (2013-2017) distribution and long-term changes of surface ozone in mainland China. Recent ozone measurements from China's air quality monitoring network (AQMN) are analyzed to show present-day distributions of a few ozone exposure metrics for urban environment. Long-term measurements of ozone at six background sites, a rural site and an urban are used to study the trends of ozone in background, rural and urban air, respectively. The average levels of ozone at the AQMN sites (mainly urban) are close to those found at many European and North American sites. However, ozone at most of the sites shows very large diurnal and seasonal variations so that ozone nonattainment can occur in many cities, particularly those in the North China Plain (NCP), the south of Northeast China (NEC), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Sichuan Basin-Chongqing region (SCB). In all these regions, particularly in the NCP, the maximum daily 8-h average (MDA8) ozone concentration can significantly exceed the national limit (75 ppb). High annual sum of ozone means over 35 ppb (SOMO35) exist mainly in the NCP, NEC and YRD, with regional averages over 4000 ppb·d. Surface ozone has significantly increased at Waliguan (a baseline site in western China) and Shangdianzi (a background site in the NCP), and decreased in winter and spring at Longfengshan (a background site in Northeast China). No clear trend can be derived from long-term measurements of ozone at other sites. Further attention should be paid to future changes of ozone in populated regions of China. Actions are urgently needed to control ozone pollution in the NCP and YRD.

Interpreting space-based trends in carbon monoxide with multiple models

DOE PAGES

Strode, Sarah A.; Worden, Helen M.; Damon, Megan; ...

2016-06-10

Here, we use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We also found that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000–2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias inmore » CO, after applying MOPITT averaging kernels, contributes to the model–observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. Our results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.« less

Interpreting space-based trends in carbon monoxide with multiple models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strode, Sarah A.; Worden, Helen M.; Damon, Megan

Here, we use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We also found that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000–2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias inmore » CO, after applying MOPITT averaging kernels, contributes to the model–observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. Our results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.« less

Interpreting Space-Based Trends in Carbon Monoxide with Multiple Models

NASA Technical Reports Server (NTRS)

Strode, Sarah A.; Worden, Helen M.; Damon, Megan; Douglass, Anne R.; Duncan, Bryan N.; Emmons, Louisa K.; Lamarque, Jean-Francois; Manyin, Michael; Oman, Luke D.; Rodriguez, Jose M.;

OZONE-ISOPRENE REACTION: RE-EXAMINATION OF THE FORMATION OF SECONDARY ORGANIC AEROSOL

EPA Science Inventory

The reaction of ozone and isoprene has been studied to examine physical and chemical characteristics of the secondary organic aerosol formed. Using a scanning mobility particle sizer, the volume distribution of the aerosol was found in the range 0.05 - 0.2 µm. The aerosol yield w...

Use of Ozone to Treat Ileostomy Dermatitis in an Experimental Rat Model.

PubMed

Biçer, Şenol; Sayar, İlyas; Gürsul, Cebrail; Işık, Arda; Aydın, Merve; Peker, Kemal; Demiryilmaz, İsmail

2016-03-07

Dermatitis associated with ileostomy is an important problem that affects many people, especially children. The aim of this study was to investigate the therapeutic effects of ozone on dermatitis due to ileostomy, and to develop an alternative treatment option. A total of 28 rats were divided into 4 groups: control, ileostomy, ozone, and zinc oxide. Ileostomy was performed in all rats except the control group. After a 1-week waiting time, the ozone group was administered ozone therapy and the zinc oxide group was administered zinc oxide cream locally once a day for a total of 7 days. All rats were sacrificed at the end of this period. The efficacy of treatment was examined by biochemical, histopathological, and immunohistochemical parameters. The levels of malondialdehyde (MDA), total glutathione (tGSH), total antioxidant capacity (TAC), and total oxidant status (TOS) were measured from tissue. Vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) were examined immunohistochemically. Dermatitis occurred pathologically in all rats that underwent ileostomy surgery. The lowest dermatitis score was in the ozone treatment group (p<0.05). Ileostomy dermatitis caused increased levels of MDA and TOS. Ozone treatment resulted in reduced MDA and TOS levels, while the levels of tGSH and TAC were increased (p<0.05). Both VEGF and PCNA immunostaining were augmented in the ozone treatment group (p<0.05). Local ozone application may be a good alternative compared to the conventional treatment methods for the prevention of skin lesions that develop after ileostomy.

Comparative Analysis of the Surface Ozone Regime Over Russia and Europe

NASA Astrophysics Data System (ADS)

Kuznetsov, G. I.; Tarasova, O. A.; Elansky, N. F.; Beloglazov, M. I.

2004-05-01

The data of the measurements of the surface ozone concentration (SOC) at several Russian cites, in TROICA expeditions, data of EMEP network as well as the results of LOTOS model application were used to compare the main characteristics of ozone spatial and temporal variability over Russia and Europe. To carry out this investigation the number of new methods of data analysis were developed and applied. Their complex application gave us possibility to separate clearly the contribution of photochemical processes having mainly periodical component (daily and seasonal). Hence more attention could be paid to the dynamical mechanism impacting SOC regime, their spatial and temporal variability including trends estimation. Spectral windowing application to the filtered database of EMEP network showed that among the different processes providing annual and shorter variability the main part (about 40% of dispersion) is governed by local and synoptical scale processes in the range of 2-7 days. At the same time the spatial distribution of these percentage contribution is non-uniform over Europe. One of the important mechanisms providing this type of variability as well as the longer ones is air transport. To study the impact of air transport the correlation fields were calculated for the transport indices using 2D NILU trajectories and SOC at EMEP network. They showed that at the Eastern border of Europe the growth of the westerlies provides not the decrease but the growth of observed SOC. This approach was use to study the features of the zonal and meridianal transport, its seasonal characteristics and annual variability. Moreover at Kislovodsk High Mountain Station the changes of the transport patters can partly explain even observed trend of SOC. Comparison of the regime at the different locations using TROICA data shows that in the most of Russian cities ozone destruction is observed. The generation of the surface ozone is only possible in the cases of combination of natural and anthropogenic emissions (like forest fires episodes in Moscow region in summer 2002). The spatial structure of the surface ozone over the European Russia was obtained with the application of LOTOS model (TNO) evaluated for 1997. It showed much more uniformity of the SOC fields over Russia with the high concentrations in rural regions in comparison with industrial ones. This conclusion is in a good agreement with the measurements of TROICA expedition. The work is carried out under the support of INTAS grant 01-0016 and RFBR 03-05-64712.

High School and College Student Perceptions of the Ozone Depletion Problem.

ERIC Educational Resources Information Center

Groves, Fred; Pugh, Ava

This paper examines the knowledge of high school biology students (n=107), undergraduate elementary education majors (n=42), and graduate students in an advanced elementary science methods course (n=22) about ozone depletion. The questionnaire used contained 30 items pertaining to ozone depletion which were divided into three subscales: (1)…

Near-ambient ozone concentrations reduce the vigor of Betula and Populus species in Finland.

PubMed

Oksanen, Elina; Manninen, Sirkku; Vapaavuori, Elina; Holopainen, Toini

2009-12-01

In this review the main growth responses of Finnish birch (Betula pendula, B. pubescens) and aspen species (Populus tremula and P. tremuloides x P. tremula) are correlated with ozone exposure, indicated as the AOT40 value. Data are derived from 23 different laboratory, open-top chamber, and free-air fumigation experiments. Our results indicate that these tree species are sensitive to increasing ozone concentrations, though high intraspecific variation exists. The roots are the most vulnerable targets in both genera. These growth reductions, determined from trees grown under optimal nutrient and water supply, were generally accompanied by increased visible foliar injuries, carbon allocation toward defensive compounds, reduced carbohydrate contents of leaves, impaired photosynthesis processes, disturbances in stomatal function, and earlier autumn senescence. Because both genera have shown complex ozone defense and response mechanisms, which are modified by variable environmental conditions, a mechanistically based approach is necessary for accurate ozone risk assessment.

Condition of The Stratospheric and Mesospheric Ozone Layer Over Bulgaria for the Period 1996-2012

NASA Astrophysics Data System (ADS)

Kaleyna, Petya; Mukhtarov, Plamen; Miloshev, Nikolay

2014-05-01

A detailed analysis of the variations of the stratospheric and mesospheric ozone over Bulgaria, in the period 1996-2012, is presented in the article on the basis of ground and satellite measurements of the Total Ozone Content (TOC). The move of the most important components: yearly running mean values, amplitudes and phases of the first four harmonics of the seasonal cycle. Their mean values for the period and the existing long term trends have been found. An evaluation of the general characteristics of the short term variability of the Total Ozone Content (TOC) over Bulgaria also has been made in the article. The impact of the planetary wave activity of the stratosphere on the total ozone has been studied and the climatology of the oscillation amplitudes with periods of 4, 7, 11 and 25 days has been defined.

An overview af SAGE I and II ozone measurements

NASA Technical Reports Server (NTRS)

Mccormick, M. P.; Zawodny, J. M.; Veiga, R. E.; Larsen, J. C.; Wang, P. H.

1989-01-01

The stratospheric Aerosol and Gas Experiments (SAGE) I and II measure Mie, Rayleigh, and gaseous extinction profiles using the solar occultation technique. These global measurements yield ozone profiles with a vertical resolution of 1 km which have been routinely obtained for the periods from February 1979 to November 1981 (SAGE I) and October 1984 to the present (SAGE II). The long-term periodic behavior of the measured ozone is presented as well as case studies of the observed short-term spatial and temporal variability. A linear regression shows annual, semiannual, and quasi-biennial oscillation features at various altitudes and latitudes which, in general, agree with past work. Also, ozone, aerosol, and water vapor data are described for the Antarctic springtime, showing large variation relative to the vortex. Cross-sections in latitude and altitude and polar plots at various altitudes clearly delineate the ozone hole vertically and areally.

An evaluation of in situ ozone sensor performance during a cold frontal passage

NASA Technical Reports Server (NTRS)

Parsons, C. L.

1978-01-01

The capabilities of the electrochemical concentration cell ozonesonde for measuring the vertical profile of atmospheric ozone were studied during a three day experiment at Wallops Island, Virginia, and Norfolk, Virginia. Using ancillary measurements at the surface and the spectrophotometer, it was concluded that the ozonesonde measures the total ozone overburden to within 10% of the real value. By releasing the balloon-borne instruments at a rate of four per day at each of the two sites, an indication was obtained of the temporal and spatial scales of atmospheric ozone variability. No significant effects of a weak cold front passage or of the loss of insolation at night were seen. An isolated incident of anomalously high ozone concentration at the peak of the profile was attributed to sporadic instrument performance effects. The data base currently available is not adequate for determining an exact cause of the anomaly.

Intercontinental Transport of Ozone from Tropical Biomass Burning

NASA Technical Reports Server (NTRS)

Thompson, A. M.

2003-01-01

Researchers have been looking at the connection between tropical biomass burning and ozone formation and long-range transport for roughly 15 years. One can see the linkage and transport patterns from satellite though aircraft and/or balloon-sonde profiles are required to observe the fine structure (ozone transport over thousands of km often happens in thin layers). In this review, I survey the pyrogenic ozone transport in the large oceanic basins - Indian Ocean, Pacific and Atlantic. Mechanistic complexities are discussed and examples shown from satellite, aircraft and soundings, including NASA results from TOMS, the GTE experiments and the SHADOZ sounding program. Experiments referred to include SAFARI-92, TRACE-A, INDOEX, PEM-Tropics and TRACE-P. augmented by subsidence, a variable tropopause height, and lightning - even ozone pollution from the Indian Ocean has been implicated. Over the Indian Ocean, pollution interacts with convection and the monsoon cycle.

Inversion structure and winter ozone distribution in the Uintah Basin, Utah, U.S.A.

NASA Astrophysics Data System (ADS)

Lyman, Seth; Tran, Trang

2015-12-01

The Uintah Basin in Utah, U.S.A. experiences high concentrations of ozone during some winters due to strong, multi-day temperature inversions that facilitate the buildup of pollution from local sources, including the oil and gas industry. Together, elevation of monitoring sites and proximity to oil and gas wells explain as much as 90% of spatial variability in surface ozone concentrations during inversion episodes (i.e., R2 = 0.90). Inversion conditions start earlier and last longer at lower elevations, at least in part because lower elevations are more insulated from winds aloft that degrade inversion conditions and dilute produced ozone. Surface air transport under inversions is dominated by light, diurnal upslope-downslope flow that limits net transport distances. Thus, different areas of the Basin are relatively isolated from each other, allowing spatial factors like elevation and proximity to sources to strongly influence ozone concentrations at individual sites.

Study of the lower stratospheric thermal structure and total ozone from Nimbus-4 IRIS

NASA Technical Reports Server (NTRS)

Prabhakara, C.

1976-01-01

The global distribution of temperature in the stratosphere from 100 to 10 mbar and the total ozone in the atmosphere are remotely sensed from the Nimbus-4 IRIS measurements for a period of about one year. The temperature and ozone data are presented in the form of monthly mean global maps. The standard deviations of temperature and ozone with respect to zonal averages are calculated. The mean and the variable state of the stratosphere are discussed with the help of these observations. The lower stratosphere in the tropical regions reveals a significant wave number one pattern in the circulation. The Arctic and Antarctic stratospheric winter circulation regimes display a different behavior apparently due to the ocean and orographic differences.

Numerical experiments on short-term meteorological effects on solar variability

NASA Technical Reports Server (NTRS)

Somerville, R. C. J.; Hansen, J. E.; Stone, P. H.; Quirk, W. J.; Lacis, A. A.

1975-01-01

A set of numerical experiments was conducted to test the short-range sensitivity of a large atmospheric general circulation model to changes in solar constant and ozone amount. On the basis of the results of 12-day sets of integrations with very large variations in these parameters, it is concluded that realistic variations would produce insignificant meteorological effects. Any causal relationships between solar variability and weather, for time scales of two weeks or less, rely upon changes in parameters other than solar constant or ozone amounts, or upon mechanisms not yet incorporated in the model.

Chemistry and Transport in a Multi-Dimensional Model

NASA Technical Reports Server (NTRS)

Yung, Yuk L.

2004-01-01

Our work has two primary scientific goals, the interannual variability (IAV) of stratospheric ozone and the hydrological cycle of the upper troposphere and lower stratosphere. Our efforts are aimed at integrating new information obtained by spacecraft and aircraft measurements to achieve a better understanding of the chemical and dynamical processes that are needed for realistic evaluations of human impact on the global environment. A primary motivation for studying the ozone layer is to separate the anthropogenic perturbations of the ozone layer from natural variability. Using the recently available merged ozone data (MOD), we have carried out an empirical orthogonal function EOF) study of the temporal and spatial patterns of the IAV of total column ozone in the tropics. The outstanding problem about water in the stratosphere is its secular increase in the last few decades. The Caltech/PL multi-dimensional chemical transport model (CTM) photochemical model is used to simulate the processes that control the water vapor and its isotopic composition in the stratosphere. Datasets we will use for comparison with model results include those obtained by the Total Ozone Mapping Spectrometer (TOMS), the Solar Backscatter Ultraviolet (SBUV and SBUV/2), Stratosphere Aerosol and Gas Experiment (SAGE I and II), the Halogen Occultation Experiment (HALOE), the Atmospheric Trace Molecular Spectroscopy (ATMOS) and those soon to be obtained by the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE) mission. The focus of the investigations is the exchange between the stratosphere and the troposphere, and between the troposphere and the biosphere.

The changing oxidizing environment in London - trends in ozone precursors and their contribution to ozone production

NASA Astrophysics Data System (ADS)

von Schneidemesser, E.; Vieno, M.; Monks, P. S.

2014-01-01

Ground-level ozone is recognized to be a threat to human health (WHO, 2003), have a deleterious impact on vegetation (Fowler et al., 2009), is also an important greenhouse gas (IPCC, 2007) and key to the oxidative ability of the atmosphere (Monks et al., 2009). Owing to its harmful effect on health, much policy and mitigation effort has been put into reducing its precursors - the nitrogen oxides (NOx) and non-methane volatile organic compounds (NMVOCs). The non-linear chemistry of tropospheric ozone formation, dependent mainly on NOx and NMVOC concentrations in the atmosphere, makes controlling tropospheric ozone complex. Furthermore, the concentration of ozone at any given point is a complex superimposition of in-situ produced or destroyed ozone and transported ozone on the regional and hemispheric-scale. In order to effectively address ozone, a more detailed understanding of its origins is needed. Here we show that roughly half (5 μg m-3) of the observed increase in urban (London) ozone (10 μg m-3) in the UK from 1998 to 2008 is owing to factors of local origin, in particular, the change in NO : NO2 ratio, NMVOC : NOx balance, NMVOC speciation, and emission reductions (including NOx titration). In areas with previously higher large concentrations of nitrogen oxides, ozone that was previously suppressed by high concentrations of NO has now been "unmasked", as in London and other urban areas of the UK. The remaining half (approximately 5 μg m-3) of the observed ozone increase is attributed to non-local factors such as long-term transport of ozone, changes in background ozone, and meteorological variability. These results show that a two-pronged approach, local action and regional-to-hemispheric cooperation, is needed to reduce ozone and thereby population exposure, which is especially important for urban ozone.

Analysis of 1970-1995 Trends in Tropospheric Ozone at Northern Hemisphere Midlatitudes with the GEOS-CHEM Model

NASA Technical Reports Server (NTRS)

Fusco, Andrew C.; Logan, Jennifer A.

2004-01-01

I ] The causes of trends in tropospheric ozone at Northern Hemisphere midlatitudes from 1970 to 1995 are investigated with the GEOS-CHEM model, a global three-dimensional model of the troposphere driven by assimilated meteorological observations from the Goddard Earth Observing System (GEOS). This model is used to investigate the sensitivity of tropospheric ozone with respect to (1) changes in the anthropogenic emission of nitrogen oxides and nonmethane hydrocarbons, (2) increases in methane concentrations, (3) variations in the stratospheric source of ozone, (4) changes in solar radiation resulting from stratospheric ozone depletion, and ( 5 ) increases in tropospheric temperatures. Model results indicate that local increases in NO, emissions have caused most of the increases seen in lower tropospheric ozone over Europe and Japan. Increases in methane are responsible for roughly one fifth of the anthropogenically induced increase in tropospheric ozone at northern midlatitudes. However, changes in ozone precursors do not adequately explain either the spatial differences in observed ozone trends across midlatitudes or the observed decreases in ozone over Canada throughout the troposphere. We argue that ozone depletion in the lowermost stratosphere is likely to have reduced the stratospheric source by as much as 30% from the early 1970s to the mid 1990s. Model simulations that account for such a reduction along with reported changes in anthropogenic emissions show steep declines of ozone in the upper troposphere and variable increases in the lower troposphere that are more consistent with observations. Differential temperature trends in summer between North America and Europe may account for at least some of the remaining spatial variation in tropospheric ozone trends. Increases in ultraviolet (UV) radiation due to stratospheric ozone depletion do not appear to significantly reduce tropospheric ozone, except at midlatitudes in the Southern Hemisphere following the breakup of the ozone hole.

Hourly air pollution concentrations and their important predictors over Houston, Texas using deep neural networks: case study of DISCOVER-AQ time period

NASA Astrophysics Data System (ADS)

Eslami, E.; Choi, Y.; Roy, A.

2017-12-01

Air quality forecasting carried out by chemical transport models often show significant error. This study uses a deep-learning approach over the Houston-Galveston-Brazoria (HGB) area to overcome this forecasting challenge, for the DISCOVER-AQ period (September 2013). Two approaches, deep neural network (DNN) using a Multi-Layer Perceptron (MLP) and Restricted Boltzmann Machine (RBM) were utilized. The proposed approaches analyzed input data by identifying features abstracted from its previous layer using a stepwise method. The approaches predicted hourly ozone and PM in September 2013 using several predictors of prior three days, including wind fields, temperature, relative humidity, cloud fraction, precipitation along with PM, ozone, and NOx concentrations. Model-measurement comparisons for available monitoring sites reported Indexes of Agreement (IOA) of around 0.95 for both DNN and RBM. A standard artificial neural network (ANN) (IOA=0.90) with similar architecture showed poorer performance than the deep networks, clearly demonstrating the superiority of the deep approaches. Additionally, each network (both deep and standard) performed significantly better than a previous CMAQ study, which showed an IOA of less than 0.80. The most influential input variables were identified using their associated weights, which represented the sensitivity of ozone to input parameters. The results indicate deep learning approaches can achieve more accurate ozone forecasting and identify the important input variables for ozone predictions in metropolitan areas.

Ozone and nitrogen oxides in surface air in Russia: TROICA experiments.

NASA Astrophysics Data System (ADS)

Pankratova, N.; Elansky, N.; Belikov, I.; Shumskiy, R.

2009-04-01

The results of measurements of surface ozone and nitrogen oxides concentrations over the continental regions of Russia are discussed. The measurements were done during 10 TROICA experiments (Transcontinental Observations Into the Chemistry of the Atmosphere). The TROICA experiment started in 1995. By the present moment ten expeditions along the Trans-Siberian railroad from Moscow to Vladivostok (around 9300 km) are carried out. We separate data sets into unpolluted and polluted areas to study temporal and spatial features. Moreover we analyzed cities (more then 100 cities). About 50% of all data corresponds to unpolluted conditions. The data collected are used in an analysis of the physical and chemical processes occurring over continental Russia. In this work the estimations of seasonal and daily ozone and NOx distribution were made. The seasonal distribution of ozone for TROICA experiments concentration considerably differs from ozone distribution at Mace Head (Ireland) and Hohenpeissenberg (Germany) stations and well agrees with the ozone distribution at Zotino (Russia, East Siberia). The same concerns also a daily variability. The ozone concentration gradient is presented. Ozone concentration gradually increases in the eastward direction. Its result of the air transport from polluted regions of Europe and ozone depletions, oxidations of CH4 in Siberia, forest fires in Siberia and around Baikal Lake, regional transport of burning products from Northern China. Significant factor of ozone increasing is stratospheric-tropospheric exchange. It appears in TROICA-3 experiment. During several hours ozone concentration was more then 60 ppbv. The areas of photochemical ozone generation in polluted air are also detected. We estimate anthropogenic and natural factors, which are responsible for sharp ozone concentration increasing. Acknowledgments. The work was supported by International Science and Technology Center (ISTC) under contract No. 2770 and by Russian Basic Research Foundation (project No. 07-05-00428).

Trend analysis of the homogenized total ozone series of Arosa (Switzerland), 1926-1996

NASA Astrophysics Data System (ADS)

Staehelin, Johannes; Kegel, Rainer; Harris, Neil R. P.

1998-04-01

Total ozone measurements have been made at Arosa, Switzerland (47°N), from 1926 through the present day, forming the longest total ozone series in the world. The record has been recently homogenized. Ozone trends are calculated to be -(2.3±0.6)% per decade for annual means (larger losses are found in winter and spring, approximately -4% per decade for trends in January, February, and March) when a simple linear change from 1970 to 1996 is assumed. In addition, total ozone trends are calculated using multiple regression models involving combinations of explanatory variables for the 11-year solar cycle, local meteorological conditions (the Mount Säntis high-altitude temperature record), stratospheric aerosol loading from volcanoes, and stratospheric chlorine loading. When the terms for the solar cycle, the stratospheric aerosol loading and the high mountain temperature record were included, the annually averaged ozone trends were found to be -(1.9±0.6)% per decade. While a statistically significant relation is found between total ozone and indices of aerosol loadings of the stratosphere, the recent decrease in total ozone cannot be accounted for by the higher average aerosol content in the second half of the century. Finally, the decrease in ozone in the stratosphere is estimated to be approximately 30% larger than that found for total ozone, when a crude estimate of the increase in tropospheric ozone is included. The acceleration observed in total ozone trends between the 1970s and the 1980s over northern midlatitudes [e.g., Harris et al., 1997] might be partially attributed to the larger increase in tropospheric ozone in the 1970s.

Behavior, distribution and variability of surface ozone at an arid region in the south of Iberian Peninsula (Seville, Spain).

PubMed

Adame, José A; Lozano, Antonio; Bolívar, Juan P; De la Morena, Benito A; Contreras, Juan; Godoy, Francisca

2008-01-01

In order to improve our knowledge of the surface ozone in the south of the Iberian Peninsula, annual, monthly, weekly and daily ozone concentrations have been closely monitored in the Seville metropolitan area highlighting those episodes that exceed the European Ozone Directive. A three-year period (2003-2005) and eight ozone stations were used; five of them located in the city's busiest areas and the rest in adjacent zones ( approximately 25km). In addition, the wind regime was also studied in order to understand the main characteristics of the surface atmospheric dynamics. The lowest ozone concentrations 17-33microgm(-3) took place in January while the highest 57-95microgm(-3) occurred in June. The ozone concentration week-weekend differences from May to September indicate that this phenomenon does not affect the ozone stations analysed. Daily cycles show minimum values between 7:00 and 8:00 UTC and maximum at noon, exceeding 90microgm(-3) during summer months. From March to October the ozone concentrations were above the target value for the protection of human health, especially during the summer months, with values up to 30% over the limit. The information threshold has been exceeded at all ozone stations studied but with greater frequency in the stations far from the city centre. In addition, at these latter stations the alert threshold was also exceeded on six occasions. This study in the city of Seville indicates that the high ozone levels are due to local atmospheric effects, mainly since the ozone air masses may undergo recirculation processes. The ozone is transported to the city from the S-SW, having a major impact in the NE areas.

Study of Ozone Layer Variability near St. Petersburg on the Basis of SBUV Satellite Measurements and Numerical Simulation (2000-2014)

NASA Astrophysics Data System (ADS)

Virolainen, Y. A.; Timofeyev, Y. M.; Smyshlyaev, S. P.; Motsakov, M. A.; Kirner, O.

2017-12-01

A comparison between the numerical simulation results of ozone fields with different experimental data makes it possible to estimate the quality of models for their further use in reliable forecasts of ozone layer evolution. We analyze time series of satellite (SBUV) measurements of the total ozone column (TOC) and the ozone partial columns in two atmospheric layers (0-25 and 25-60 km) and compare them with the results of numerical simulation in the chemistry transport model (CTM) for the low and middle atmosphere and the chemistry climate model EMAC. The daily and monthly average ozone values, short-term periods of ozone depletion, and long-term trends of ozone columns are considered; all data sets relate to St. Petersburg and the period between 2000 and 2014. The statistical parameters (means, standard deviations, variations, medians, asymmetry parameter, etc.) of the ozone time series are quite similar for all datasets. However, the EMAC model systematically underestimates the ozone columns in all layers considered. The corresponding differences between satellite measurements and EMAC numerical simulations are (5 ± 5)% and (7 ± 7)% and (1 ± 4)% for the ozone column in the 0-25 and 25-60 km layers, respectively. The correspondent differences between SBUV measurements and CTM results amount to (0 ± 7)%, (1 ± 9)%, and (-2 ± 8)%. Both models describe the sudden episodes of the ozone minimum well, but the EMAC accuracy is much higher than that of the CTM, which often underestimates the ozone minima. Assessments of the long-term linear trends show that they are close to zero for all datasets for the period under study.

Spatio-temporal observations of tertiary ozone maximum

NASA Astrophysics Data System (ADS)

Sofieva, V. F.; Kyrölä, E.; Verronen, P. T.; Seppälä, A.; Tamminen, J.; Marsh, D. R.; Smith, A. K.; Bertaux, J.-L.; Hauchecorne, A.; Dalaudier, F.; Fussen, D.; Vanhellemont, F.; Fanton D'Andon, O.; Barrot, G.; Guirlet, M.; Fehr, T.; Saavedra, L.

2009-03-01

We present spatio-temporal distributions of tertiary ozone maximum (TOM), based on GOMOS (Global Ozone Monitoring by Occultation of Stars) ozone measurements in 2002-2006. The tertiary ozone maximum is typically observed in the high-latitude winter mesosphere at altitude ~72 km. Although the explanation for this phenomenon has been found recently - low concentrations of odd-hydrogen cause the subsequent decrease in odd-oxygen losses - models have had significant deviations from existing observations until recently. Good coverage of polar night regions by GOMOS data has allowed for the first time obtaining spatial and temporal observational distributions of night-time ozone mixing ratio in the mesosphere. The distributions obtained from GOMOS data have specific features, which are variable from year to year. In particular, due to a long lifetime of ozone in polar night conditions, the downward transport of polar air by the meridional circulation is clearly observed in the tertiary ozone maximum time series. Although the maximum tertiary ozone mixing ratio is achieved close to the polar night terminator (as predicted by the theory), TOM can be observed also at very high latitudes, not only in the beginning and at the end, but also in the middle of winter. We have compared the observational spatio-temporal distributions of tertiary ozone maximum with that obtained using WACCM (Whole Atmosphere Community Climate Model) and found that the specific features are reproduced satisfactorily by the model. Since ozone in the mesosphere is very sensitive to HOx concentrations, energetic particle precipitation can significantly modify the shape of the ozone profiles. In particular, GOMOS observations have shown that the tertiary ozone maximum was temporarily destroyed during the January 2005 and December 2006 solar proton events as a result of the HOx enhancement from the increased ionization.

Spatio-temporal observations of the tertiary ozone maximum

NASA Astrophysics Data System (ADS)

Sofieva, V. F.; Kyrölä, E.; Verronen, P. T.; Seppälä, A.; Tamminen, J.; Marsh, D. R.; Smith, A. K.; Bertaux, J.-L.; Hauchecorne, A.; Dalaudier, F.; Fussen, D.; Vanhellemont, F.; Fanton D'Andon, O.; Barrot, G.; Guirlet, M.; Fehr, T.; Saavedra, L.

2009-07-01

We present spatio-temporal distributions of the tertiary ozone maximum (TOM), based on GOMOS (Global Ozone Monitoring by Occultation of Stars) ozone measurements in 2002-2006. The tertiary ozone maximum is typically observed in the high-latitude winter mesosphere at an altitude of ~72 km. Although the explanation for this phenomenon has been found recently - low concentrations of odd-hydrogen cause the subsequent decrease in odd-oxygen losses - models have had significant deviations from existing observations until recently. Good coverage of polar night regions by GOMOS data has allowed for the first time to obtain spatial and temporal observational distributions of night-time ozone mixing ratio in the mesosphere. The distributions obtained from GOMOS data have specific features, which are variable from year to year. In particular, due to a long lifetime of ozone in polar night conditions, the downward transport of polar air by the meridional circulation is clearly observed in the tertiary ozone maximum time series. Although the maximum tertiary ozone mixing ratio is achieved close to the polar night terminator (as predicted by the theory), TOM can be observed also at very high latitudes, not only in the beginning and at the end, but also in the middle of winter. We have compared the observational spatio-temporal distributions of the tertiary ozone maximum with that obtained using WACCM (Whole Atmosphere Community Climate Model) and found that the specific features are reproduced satisfactorily by the model. Since ozone in the mesosphere is very sensitive to HOx concentrations, energetic particle precipitation can significantly modify the shape of the ozone profiles. In particular, GOMOS observations have shown that the tertiary ozone maximum was temporarily destroyed during the January 2005 and December 2006 solar proton events as a result of the HOx enhancement from the increased ionization.

Seasonal ozone levels and control by seasonal meteorology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagnotti, V.

1990-02-01

Meteorological data, particularly 850-MB level temperatures, for Fort Totten, New York (1980) and Atlantic City, New Jersey (1981-1988) were examined for any relationship to seasonal ozone levels. Other radiosonde stations in the Northeast were utilized for 1983 and 1986, years of widely differing ozone levels. Statistics for selected parameters and years are presented. Emphasis is placed on recurring warm temperature regimes in high ozone years. Successive occurrences or episodes of high temperatures characterize seasonally high ozone years. Seasonally persistent high temperatures are related to seasonally chronic high ozone. An example is presented relating the broad-scale climatologically anomalous pattern of highmore » temperatures to anomalous circulation patterns at the 700-MB level.« less

Influence of isoprene chemical mechanism on modelled changes in tropospheric ozone due to climate and land use over the 21st century

NASA Astrophysics Data System (ADS)

Squire, O. J.; Archibald, A. T.; Griffiths, P. T.; Jenkin, M. E.; Pyle, J. A.

2014-09-01

Isoprene is a precursor to tropospheric ozone, a key pollutant and greenhouse gas. Anthropogenic activity over the coming century is likely to cause large changes in atmospheric CO2 levels, climate and land use, all of which will alter the global vegetation distribution leading to changes in isoprene emissions. Previous studies have used global chemistry-climate models to assess how possible changes in climate and land use could affect isoprene emissions and hence tropospheric ozone. The chemistry of isoprene oxidation, which can alter the concentration of ozone, is highly complex, therefore it must be parameterised in these models. In this work we compare the effect of four different reduced isoprene chemical mechanisms, all currently used in Earth-system models, on tropospheric ozone. Using a box model we compare ozone in these reduced schemes to that in a more explicit scheme (the MCM) over a range of NOx and isoprene emissions, through the use of O3 isopleths. We find that there is some variability, especially at high isoprene emissions, caused by differences in isoprene-derived NOx reservoir species. A global model is then used to examine how the different reduced schemes respond to potential future changes in climate, isoprene emissions, anthropogenic emissions and land use change. We find that, particularly in isoprene rich regions, the response of the schemes varies considerably. The wide ranging response is due to differences in the types of peroxy radicals produced by isoprene oxidation, and their relative rates of reaction towards NO, leading to ozone formation, or HO2, leading to termination. Also important is the yield of isoprene-nitrates and peroxyacyl nitrate precursors from isoprene oxidation. Those schemes that produce less of these NOx reservoir species, tend to produce more ozone locally and less away from the source region. Additionally, by combining the emissions and O3 data from all of the global model integrations, we are able to construct isopleth plots comparable to those from the box model analysis. We find that the global and box model isopleths show good qualitative agreement, suggesting that comparing chemical mechanisms with a box model in this framework is a useful tool for assessing mechanistic performance in complex global models. We conclude that as the choice of reduced isoprene mechanism may alter both the magnitude and sign of the ozone response, how isoprene chemistry is parameterised in perturbation experiments such as these is a crucially important consideration. More measurements are needed to validate these reduced mechanisms especially in high-VOC, low-NOx environments.

User's guide for the Solar Backscattered Ultraviolet (SBUV) instrument first year ozone-S data set

NASA Technical Reports Server (NTRS)

Fleig, A. J.; Klenk, K. F.; Bhartia, P. K.; Gordon, D.; Schneider, W. H.

1982-01-01

Total-ozone and ozone vertical profile results for Solar Backscattered Ultraviolet/Total Ozone Mapping Spectrometer (SBUV/TOMS) Nimbus 7 operation from November 1978 to November 1979 are available. The algorithm used have been thoroughly tested, the instrument performance has been examined in details, and the ozone results have been compared with Dobson, Umkehr, balloon, and rocket observations. The accuracy and precision of the satellite ozone data are good to at least within the ability of the ground truth to check and are self-consistent to within the specifications of the instrument. The 'SBUV User's Guide' describes the SBUV experiment and algorithms used. Detailed information on the data available on computer tape is provided including how to order tapes from the National Space Science Data Center.

Generation and Reduction of NOx on Air-Fed Ozonizers

NASA Astrophysics Data System (ADS)

Ehara, Yoshiyasu; Amemiya, Yusuke; Yamamoto, Toshiaki

A generation and reduction of NOx on air-fed ozonizers using a ferroelectric packed bed reactor have been experimentally investigated. The reactors packed with CaTiO3, SrTiO3 and BaTiO3 pellets are examined for ozone generation. An ac voltage is applied to the reactor to generate partial discharge. Ozone concentration and the different nitrogen oxides at downstream of the packed bed reactor were measured with UV absorption ozone monitor and a Fourier transform infrared spectroscope respectively. The dielectric constant of packed ferroelectric pellets influences the discharge characteristic, ozone and NOx generations are varied by the dielectric constant value. Focusing on a discharge pulse current and maximum discharge magnitude, the ferroelectric packed bed plasma reactors have been evaluated on nitrogen oxide and ozone generated concentrations.

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.

Study of air pollution: Effects of ozone on neuropeptide-mediated responses in human subjects. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boushey, H.A.

1991-11-01

The study examined the hypothesis that ozone inactivates the enzyme, neutral endopeptidase, responsible for limiting the effects of neuropeptides released from afferent nerve endings. Cough response of capsaicin solution delivered from a nebulizer at 2 min. intervals until two or more coughs were produced. Other endpoints measured included irritative symptoms as rated by the subjects on a nonparametric scale, spirometry, of each concentration of ozone were compared to those of filtered air in a single-blind randomized sequence. The results indicate that a 2 h. exposure to 0.4 ppm of ozone with intermittent light exercise alters the sensitivity of airway nervesmore » that mediate the cough response to inhaled materials. This dose of ozone also caused a change in FEV1. A lower level of ozone, 0.02 ppm, caused a change in neither cough threshold nor FEV1, even when the duration of exposure was extended to three hours. The findings are consistent with the author's hypothesis that ozone may sensitize nerve endings in the airways by inactivating neutral endopeptidase, an enzyme that regulates their activity, but they do not demonstrate that directly examining an effect directly mediated by airway nerves allows detection of effects of ozone at doses below those causing effects detected by standard tests of pulmonary function.« less

Wintertime ozone and nitrogen oxide photochemistry and nighttime chemistry in a Western oil and gas basin

NASA Astrophysics Data System (ADS)

Brown, S. S.; Edwards, P. M.; Patel, S.; Dube, W. P.; Williams, E. J.; Roberts, J. M.; McLaren, R.; Kercher, J. P.; Gilman, J. B.; Lerner, B. M.; Warneke, C.; Geiger, F.; De Gouw, J. A.; Tsai, C.; Stutz, J.; Young, C. J.; Washenfelder, R. A.; Parrish, D. D.

2012-12-01

Oil and gas development in mountain basins of the Western United States has led to frequent exceedences of National Ambient Air Quality Standards for ozone during the winter season. The Uintah Basin Winter Ozone Study took place during February and March 2012 in northeast Utah with the goal of providing detailed chemical and meteorological data to understand this phenomenon. Although snow and cold pool stagnation conditions that lead to winter ozone buildup were not encountered during the study period, the detailed measurements did provide a unique data set to understand the chemistry of key air pollutants in a desert environment during winter. This presentation will examine both the photochemistry and the nighttime chemistry of nitrogen oxides, ozone and VOCs, with the goal of understanding the observed photochemistry and its relationship to nighttime chemistry through a set of box models. The photochemical box model is based on the master chemical mechanism (MCM), a detailed model for VOC degradation and ozone production. The presentation will examine the sensitivity of ozone photochemistry to different parameters, including pollutant concentrations likely to be characteristic of cold pool conditions, and the strength of radical sources derived from heterogeneous chemical reactions. The goal of the analysis will be to identify the factors most likely to be responsible for the higher ozone events that have been observed during colder years with less detailed chemical measurements.

Temperature, ozone, and mortality in urban and non-urban counties in the northeastern United States.

PubMed

Madrigano, Jaime; Jack, Darby; Anderson, G Brooke; Bell, Michelle L; Kinney, Patrick L

2015-01-07

Most health effects studies of ozone and temperature have been performed in urban areas, due to the available monitoring data. We used observed and interpolated data to examine temperature, ozone, and mortality in 91 urban and non-urban counties. Ozone measurements were extracted from the Environmental Protection Agency's Air Quality System. Meteorological data were supplied by the National Center for Atmospheric Research. Observed data were spatially interpolated to county centroids. Daily internal-cause mortality counts were obtained from the National Center for Health Statistics (1988-1999). A two-stage Bayesian hierarchical model was used to estimate each county's increase in mortality risk from temperature and ozone. We examined county-level associations according to population density and compared urban (≥1,000 persons/mile(2)) to non-urban (<1,000 persons/mile(2)) counties. Finally, we examined county-level characteristics that could explain variation in associations by county. A 10 ppb increase in ozone was associated with a 0.45% increase in mortality (95% PI: 0.08, 0.83) in urban counties, while this same increase in ozone was associated with a 0.73% increase (95% PI: 0.19, 1.26) in non-urban counties. An increase in temperature from 70°F to 90°F (21.2°C 32.2°C) was associated with a 8.88% increase in mortality (95% PI: 7.38, 10.41) in urban counties and a 8.08% increase (95% PI: 6.16, 10.05) in non-urban counties. County characteristics, such as population density, percentage of families living in poverty, and percentage of elderly residents, partially explained the variation in county-level associations. While most prior studies of ozone and temperature have been performed in urban areas, the impacts in non-urban areas are significant, and, for ozone, potentially greater. The health risks of increasing temperature and air pollution brought on by climate change are not limited to urban areas.

Ozone and caries: a review of the literature.

PubMed

Burke, F J Trevor

2012-05-01

Ozone, either in gaseous form or as ozonated water, has been available for use as a treatment for dental caries for a decade. This paper reviews the literature on the subject by examining the findings of publications in the peer review literature. Eighteen papers were identified by a literature search. From the review of these, it was concluded that, while some laboratory studies and some short duration clinical studies have suggested that ozone may be effective in the treatment of root caries or killing of oral micro-organisms, the clinical evidence for the use of ozone in treatment of caries is not compelling.

Lichens, ozone, and forest health - exploring cross-indicator analyses with FIA data

Treesearch

Susan Will-Wolf; Sarah Jovan

2009-01-01

Does air pollution risk represented by a lichen bioindicator of air pollution, an ozone bioindicator, or a combination of both, correlate with forest health as reflected by condition of tree crowns and other variables? We conducted pilot analyses to answer this question using Forest Inventory and Analysis (FIA) data from the Sierra Nevada region of California and the...

Attribution of Recovery in Lower-Stratospheric Ozone

NASA Technical Reports Server (NTRS)

Yang, Eun-Su; Cunnold, Derek M.; Salawitch, Ross J.; McCormick, M. Patrick; Russell, James, III; Zawodny, Joseph M.; Oltmans, Samuel; Newchurch, Michael J.

2005-01-01

Multiple satellite and ground-based observations provide consistent evidence that the thickness of Earth's protective ozone layer has stopped declining since 1997, close to the time of peak stratospheric halogen loading. Regression analyses with Effective Equivalent Stratospheric Chlorine (EESC) in conjunction with further analyses using more sophisticated photochemical model calculations constrained by satellite data demonstrate that the cessation of ozone depletion between 18-25 km altitude is consistent with a leveling off of stratospheric abundances of chlorine and bromine, due to the Montreal Protocol and its amendments. However, ozone increases in the lowest part of the stratosphere, from the tropopause to 18 km, account for about half of the improvement in total column ozone during the past 9 years at northern hemisphere mid-latitudes. The increase in ozone for altitudes below 18 km is most likely driven by changes in transport, rather than driven by declining chlorine and bromine. Even with this evidence that the Montreal Protocol and its amendments are having the desired, positive effect on ozone above 18 km, total column ozone is recovering faster than expected due to the apparent transport driven changes at lower altitudes. Accurate prediction of future levels of stratospheric ozone will require comprehensive understanding of the factors that drive temporal changes at various altitudes, and partitioning of the recent transport-driven increases between natural variability and changes in atmospheric structure perhaps related to anthropogenic climate change.

Attribution of Recovery in Lower-stratospheric Ozone

NASA Technical Reports Server (NTRS)

Yang, Eun-Su; Cunnold, Derek M.; Salawitch, Ross J.; McCormick, M. Patrick; Russell, James, III; Zawodny, Joseph M.; Oltmans, Samuel; Newchurch, Michael J.

2006-01-01

Multiple satellite and ground-based observations provide consistent evidence that the thickness of Earth's protective ozone layer has stopped declining since 1997, close to the time of peak stratospheric halogen loading. Regression analyses with Effective Equivalent Stratospheric Chlorine (EESC) in conjunction with further analyses using more sophisticated photochemical model calculations constrained by satellite data demonstrate that the cessation of ozone depletion between 18-25 km altitude is consistent with a leveling off of stratospheric abundances of chlorine and bromine, due to the Montreal Protocol and its amendments. However, ozone increases in the lowest part of the stratosphere, from the tropopause to 18 km, account for about half of the improvement in total column ozone during the past 9 years at northern hemisphere mid-latitudes. The increase in ozone for altitudes below 18 km is most likely driven by changes in transport, rather than driven by declining chlorine and bromine. Even with this evidence that the Montreal Protocol and its amendments are having the desired, positive effect on ozone above 18 km, total column ozone is recovering faster than expected due to the apparent transport driven changes at lower altitudes. Accurate prediction of future levels of stratospheric ozone will require comprehensive understanding of the factors that drive temporal changes at various altitudes, and partitioning of the recent transport-driven increases between natural variability and changes in atmospheric structure perhaps related to anthropogenic climate change.

Northern Hemisphere Winter Climate Response to Greenhouse Gas, Ozone, Solar and Volcanic Forcing

NASA Technical Reports Server (NTRS)

Shindell, Drew T.; Schmidt, Gavin A.; Miller, Ron L.; Rind, David; Hansen, James E. (Technical Monitor)

2001-01-01

The Goddard Institute for Space Studies (GISS) climate/middle atmosphere model has been used to study the impacts of increasing greenhouse gases, polar ozone depletion, volcanic eruptions, and solar cycle variability. We focus on the projection of the induced responses onto Northern Hemisphere winter surface climate. Changes in the model's surface climate take place largely through enhancement of existing variability patterns, with greenhouse gases, polar ozone depletion and volcanic eruptions primarily affecting the Arctic Oscillation (AO) pattern. Perturbations descend from the stratosphere to the surface in the model by altering the propagation of planetary waves coming up from the surface, in accord with observational evidence. Models lacking realistic stratospheric dynamics fail to capture these wave flux changes. The results support the conclusion that the stratosphere plays a crucial role in recent AO trends. We show that in our climate model, while ozone depletion has a significant effect, greenhouse gas forcing is the only one capable of causing the large, sustained increase in the AO observed over recent decades. This suggests that the AO trend, and a concurrent strengthening of the stratospheric vortex over the Arctic, are very likely anthropogenic in origin.

Evaluation of a Multi-Decadal Simulation of Stratospheric Ozone by Comparison with Total Ozone Mapping Spectrometer (TOMS) Observations

NASA Technical Reports Server (NTRS)

Douglass, Anne R.; Stolarski, Richard S.; Steenrod, Steven; Pawson, Steven

2003-01-01

One key application of atmospheric chemistry and transport models is prediction of the response of ozone and other constituents to various natural and anthropogenic perturbations. These include changes in composition, such as the previous rise and recent decline in emission of man-made chlorofluorcarbons, changes in aerosol loading due to volcanic eruption, and changes in solar forcing. Comparisons of hindcast model results for the past few decades with observations are a key element of model evaluation and provide a sense of the reliability of model predictions. The 25 year data set from Total Ozone Mapping Spectrometers is a cornerstone of such model evaluation. Here we report evaluation of three-dimensional multi-decadal simulation of stratospheric composition. Meteorological fields for this off-line calculation are taken from a 50 year simulation of a general circulation model. Model fields are compared with observations from TOMS and also with observations from the Stratospheric Aerosol and Gas Experiment (SAGE), Microwave Limb Sounder (MLS), Cryogenic Limb Array Etalon Spectrometer (CLAES), and the Halogen Occultation Experiment (HALOE). This overall evaluation will emphasize the spatial, seasonal, and interannual variability of the simulation compared with observed atmospheric variability.

Observations of, and sources of the spatial and temporal variability of ozone in the middle atmosphere on climatological time scales (OZMAP) and equatorial dynamics: Seasonal variations of ozone trends

NASA Technical Reports Server (NTRS)

Entzian, G.; Grasnick, K. H.; Taubenheim, J.

1989-01-01

The long term trends (least square linear regression with time) of ozone content at seven European, seven North American, three Japanese and two tropical stations during 21 years (1964 to 1984) are analyzed. In all regions negative trends are observed during the 1970s, but are partly compensated by limited periods of positive trends during the late 1960s and late 1970s. Solely the North American ozone data show negative trends in all 10 year periods. When the long term ozone trends are evaluated for each month of the year separately, a seasonal variation is revealed, which in Europe and North America has largest negative trends in late winter and spring. While in Europe the negative trends in winter/spring are partly compensated by positive trends in summer, in North America the summer values reach only zero, retaining the significant negative trend in annual mean values. In contrast to the antarctic ozone hole, the spring reduction of ozone in Europe and in North America is associated with stratospheric temperatures increasing in the analyzed period and therefore is consistent with the major natural ozone production and loss processes.

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.

Tropospheric ozone variability over Singapore from August 1996 to December 1999

NASA Astrophysics Data System (ADS)

Yonemura, S.; Tsuruta, H.; Maeda, T.; Kawashima, S.; Sudo, S.; Hayashi, M.

Vertical ozone profiles over Singapore (lat 1°20'N, long 103°53'E) have been monitored by ozonesondes twice a month since August 1996. We report the vertical ozone profiles over Singapore from August 1996 to the end of 1999. During this time, large ozone enhancements occurred during three periods: March-June 1997, September-November 1997, and February-May 1998. These ozone enhancements were larger over Singapore than over Malaysia. Backward trajectory analyses revealed that the enhancements during September-November 1997, and February-May 1998 were associated with biomass burning in Indonesia and Southeast Asia. Outside the three periods, ozone concentrations over Singapore differed from those over Malaysia by not more than 2.5% at altitudes of between 2.6 and 7.6 km and by not more than 12% at altitudes of between 1 and 13.5 km. The minimum ozone concentrations in the middle and the upper troposphere were about 20 ppbv and were observed when the wind was easterly from the Pacific Ocean. Ozone concentrations at the bottom of the troposphere were near zero when the wind was southerly to westerly (from the larger, more urbanized and industrialized part of Singapore and the Strait of Malacca), implying that ozone-destroying reactions were occurring with high concentrations of urban pollutants. We conclude that the ozone enhancements observed in the free troposphere resulted from the effects of extensive biomass burning combined with the modified circulation (suppressed convection of maritime air masses) that occurs during El Niño events.

Tropospheric Ozone as a Short-lived Chemical Climate Forcer

NASA Technical Reports Server (NTRS)

Pickering, Kenneth E.

2012-01-01

Tropospheric ozone is the third most important greenhouse gas according to the most recent IPCC assessment. However, tropospheric ozone is highly variable in both space and time. Ozone that is located in the vicinity of the tropopause has the greatest effect on climate forcing. Nitrogen oxides (NOx) are the most important precursors for ozone In most of the troposphere. Therefore, pollution that is lofted upward in thunderstorm updrafts or NOx produced by lightning leads to efficient ozone production in the upper troposphere, where ozone is most important climatically. Global and regional model estimates of the impact of North American pollution and lightning on ozone radiative forcing will be presented. It will be shown that in the Northern Hemisphere summer, the lightning effect on ozone radiative forcing can dominate over that of pollution, and that the radiative forcing signal from North America extends well into Europe and North Africa. An algorithm for predicting lightning flash rates and estimating lightning NOx emissions is being incorporated into the NASA GEOS-5 Chemistry and Climate Model. Changes in flash rates and emissions over an ENSO cycle and in future climates will be assessed, along with the resulting changes in upper tropospheric ozone. Other research on the production of NOx per lightning flash and its distribution in the vertical based on cloud-resolving modeling and satellite observations will be presented. Distributions of NO2 and O3 over the Middle East from the OMI instrument on NASA's Aura satellite will also be shown.

Stratospheric ozone variations in the equatorial region as seen in Stratiospheric Aerosol and Gas Experiment data

NASA Technical Reports Server (NTRS)

Shiotani, Masato; Hasebe, Fumio

1994-01-01

An analysis is made of equatorial ozone variations for 5 years, 1984-1989, using the ozone profile data derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument. Attention is focused on the annual cycle and also on interannual variability, particularly the quasi-biennial oscillation (QBO) and El Nino-Southern Oscillation (ENSO) variations in the lower stratosphere, where the largest contribution to total column ozone takes place. The annual variation in zonal mean total ozone around the equator is composed of symmetric and asymmetric modes with respect to the equator, with maximum contributions being around 19 km for the symmetric mode and around 25 km for the asymmetric mode. The persistent zonal wavenumber 1 structure observed by the total ozone mapping spectrometer over the equator is almost missing in the SAGE-derived column amounts integrated in the stratosphere, suggesting a significant contribution from tropospheric ozone. Interannual variations in the equatorial ozone are dominated by the QBO above 20 km and the ENSO-related variation below 20 km. The ozone QBO is characterized by zonally uniform phase changes in association with the zonal wind QBO in the equatorial lower stratosphere. The ENSO-related ozone variation consists of both the east-west vacillation and the zonally uniform phase variation. During the El Nino event, the east-west contrast with positive (negative) deviations in the eastern (western) hemisphere is conspicuous, while the decreasing tendency of the zonal mean values is maximum at the same time.

Characterization of Vertical Ozonesonde Measurements in Equatorial Regions Utilizing the Cooperative Enterprise SHADOZ

NASA Technical Reports Server (NTRS)

Schmidlin, F. J.; Thompson, A. M.; Holdren, D. H.; Northam, E. T.; Witte, J. C.; Oltmans, S. J.; Hoegger, B.; Levrat, G. M.; Kirchhoff, V.

2000-01-01

Vertical ozone profiles between the Equator and 10 S latitude available from the Southern Hemisphere Additional Ozone (SHADOZ) program provide consistent data Ozone sets from up to 10 sounding locations. SHADOZ designed to provide independent ozone profiles in the tropics for evaluation of satellite ozone data and models has made available over 600 soundings over the period 1998-1999. These observations provide an ideal data base for the detailed description of ozone and afford differential comparison between sites. TOMS total ozone when compared with correlative integrated total ozone overburden from the sondes is found to be negatively biased when using the classical constant mixing ratio procedure to determine residual ozone. On the other hand, the climatological method proposed by McPeters and Labow appears to give consistent results but is positively biased. The longer then two years series of measurements also was subjected to harmonic analysis to examine data cycles. These will be discussed as well.

Ozone Exposure, Cardiopulmonary Health, and Obesity: A Substantive Review.

PubMed

Koman, Patricia D; Mancuso, Peter

2017-07-17

From 1999-2014, obesity prevalence increased among adults and youth. Obese individuals may be uniquely susceptible to the proinflammatory effects of ozone because obese humans and animals have been shown to experience a greater decline in lung function than normal-weight subjects. Obesity is independently associated with limitations in lung mechanics with increased ozone dose. However, few epidemiologic studies have examined the interaction between excess weight and ozone exposure among adults. Using PubMed keyword searches and reference lists, we reviewed epidemiologic evidence to identify potential response-modifying factors and determine if obese or overweight adults are at increased risk of ozone-related health effects. We initially identified 170 studies, of which seven studies met the criteria of examining the interaction of excess weight and ozone exposure on cardiopulmonary outcomes in adults, including four short-term ozone exposure studies in controlled laboratory settings and three community epidemiologic studies. In the studies identified, obesity was associated with decreased lung function and increased inflammatory mediators. Results were inconclusive about the effect modification when data were stratified by sex. Obese and overweight populations should be considered as candidate at-risk groups for epidemiologic studies of cardiopulmonary health related to air pollution exposures. Air pollution is a modifiable risk factor that may decrease lung function among obese individuals with implications for environmental and occupational health policy.

Structure and Dynamics of the Quasi-Biennial Oscillation in MERRA-2.

PubMed

Coy, Lawrence; Wargan, Krzysztof; Molod, Andrea M; McCarty, William R; Pawson, Steven

2016-07-01

The structure, dynamics, and ozone signal of the Quasi-Biennial Oscillation produced by the 35-year NASA MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications) reanalysis are examined based on monthly mean output. Along with the analysis of the QBO in assimilation winds and ozone, the QBO forcings created by assimilated observations, dynamics, parameterized gravity wave drag, and ozone chemistry parameterization are examined and compared with the original MERRA system. Results show that the MERRA-2 reanalysis produces a realistic QBO in the zonal winds, mean meridional circulation, and ozone over the 1980-2015 time period. In particular, the MERRA-2 zonal winds show improved representation of the QBO 50 hPa westerly phase amplitude at Singapore when compared to MERRA. The use of limb ozone observations creates improved vertical structure and realistic downward propagation of the ozone QBO signal during times when the MLS ozone limb observations are available (October 2004 to present). The increased equatorial GWD in MERRA-2 has reduced the zonal wind data analysis contribution compared to MERRA so that the QBO mean meridional circulation can be expected to be more physically forced and therefore more physically consistent. This can be important for applications in which MERRA-2 winds are used to drive transport experiments.

Structure and Dynamics of the Quasi-Biennial Oscillation in MERRA-2

PubMed Central

Coy, Lawrence; Wargan, Krzysztof; Molod, Andrea M.; McCarty, William R.; Pawson, Steven

2018-01-01

The structure, dynamics, and ozone signal of the Quasi-Biennial Oscillation produced by the 35-year NASA MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications) reanalysis are examined based on monthly mean output. Along with the analysis of the QBO in assimilation winds and ozone, the QBO forcings created by assimilated observations, dynamics, parameterized gravity wave drag, and ozone chemistry parameterization are examined and compared with the original MERRA system. Results show that the MERRA-2 reanalysis produces a realistic QBO in the zonal winds, mean meridional circulation, and ozone over the 1980–2015 time period. In particular, the MERRA-2 zonal winds show improved representation of the QBO 50 hPa westerly phase amplitude at Singapore when compared to MERRA. The use of limb ozone observations creates improved vertical structure and realistic downward propagation of the ozone QBO signal during times when the MLS ozone limb observations are available (October 2004 to present). The increased equatorial GWD in MERRA-2 has reduced the zonal wind data analysis contribution compared to MERRA so that the QBO mean meridional circulation can be expected to be more physically forced and therefore more physically consistent. This can be important for applications in which MERRA-2 winds are used to drive transport experiments. PMID:29551854

Detection and measurement of total ozone from stellar spectra: Paper 2. Historic data from 1935-1942

NASA Astrophysics Data System (ADS)

Griffin, R. E. M.

2006-06-01

Atmospheric ozone columns are derived from historic stellar spectra observed between 1935 and 1942 at Mount Wilson Observatory, California. Comparisons with contemporary measurements in the Arosa database show a generally close correspondence, while a similar comparison with more sparse data from Table Mountain reveals a difference of ~15-20%, as has also been found by other researches of the latter data. The results of the analysis indicate that astronomy's archives command considerable potential for investigating the natural levels of ozone and its variability during the decades prior to anthropogenic interference.

Children's Ideas about the Ozone Layer and Opportunities for Physics Teaching.

ERIC Educational Resources Information Center

Potts, Alison; And Others

1996-01-01

Examines the potential of global environmental issues as starting points for learning science by studying the preconceptions of children aged 12-13 about the nature, functions, and vulnerability of the ozone layer. Results indicate that children are familiar with the location and nature of the ozone layer but less informed about its magnitude and…

Antarctic Ozone Hole on September 17, 2001

NASA Technical Reports Server (NTRS)

2002-01-01

Satellite data show the area of this year's Antarctic ozone hole peaked at about 26 million square kilometers-roughly the size of North America-making the hole similar in size to those of the past three years, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). Researchers have observed a leveling-off of the hole size and predict a slow recovery. Over the past several years the annual ozone hole over Antarctica has remained about the same in both its size and in the thickness of the ozone layer. 'This is consistent with human-produced chlorine compounds that destroy ozone reaching their peak concentrations in the atmosphere, leveling off, and now beginning a very slow decline,' said Samuel Oltmans of NOAA's Climate Monitoring and Diagnostics Laboratory, Boulder, Colo. In the near future-barring unusual events such as explosive volcanic eruptions-the severity of the ozone hole will likely remain similar to what has been seen in recent years, with year-to-year differences associated with meteorological variability. Over the longer term (30-50 years) the severity of the ozone hole in Antarctica is expected to decrease as chlorine levels in the atmosphere decline. The image above shows ozone levels on Spetember 17, 2001-the lowest levels observed this year. Dark blue colors correspond to the thinnest ozone, while light blue, green, and yellow pixels indicate progressively thicker ozone. For more information read: 2001 Ozone Hole About the Same Size as Past Three Years. Image courtesy Greg Shirah, GSFC Scientific Visualization Studio, based on data from the TOMS science team

Analysis of the Latitudinal Variability of Tropospheric Ozone in the Arctic Using the Large Number of Aircraft and Ozonesonde Observations in Early Summer 2008

NASA Technical Reports Server (NTRS)

Ancellet, Gerard; Daskalakis, Nikos; Raut, Jean Christophe; Tarasick, David; Hair, Jonathan; Quennehen, Boris; Ravetta, Francois; Schlager, Hans; Weinheimer, Andrew J.; Thompson, Anne M.;

Estimating Uncertainty in Long Term Total Ozone Records from Multiple Sources

NASA Technical Reports Server (NTRS)

Frith, Stacey M.; Stolarski, Richard S.; Kramarova, Natalya; McPeters, Richard D.

2014-01-01

Total ozone measurements derived from the TOMS and SBUV backscattered solar UV instrument series cover the period from late 1978 to the present. As the SBUV series of instruments comes to an end, we look to the 10 years of data from the AURA Ozone Monitoring Instrument (OMI) and two years of data from the Ozone Mapping Profiler Suite (OMPS) on board the Suomi National Polar-orbiting Partnership satellite to continue the record. When combining these records to construct a single long-term data set for analysis we must estimate the uncertainty in the record resulting from potential biases and drifts in the individual measurement records. In this study we present a Monte Carlo analysis used to estimate uncertainties in the Merged Ozone Dataset (MOD), constructed from the Version 8.6 SBUV2 series of instruments. We extend this analysis to incorporate OMI and OMPS total ozone data into the record and investigate the impact of multiple overlapping measurements on the estimated error. We also present an updated column ozone trend analysis and compare the size of statistical error (error from variability not explained by our linear regression model) to that from instrument uncertainty.

Comparison of SAGE II ozone measurements and ozone soundings at Uccle (Belgium) during the period February 1985 to January 1986

NASA Technical Reports Server (NTRS)

De Muer, D.; De Backer, H.; Zawodny, J. M.; Veiga, R. E.

1990-01-01

The ozone profiles obtained from 24 balloon soundings at Uccle (50 deg 48 min N, 4 deg 21 min E) made with electrochemical ozonesondes were used as correlative data for SAGE II ozone profiles retrieved within a distance of at most 600 km from Uccle. The agreement between the two data sets is in general quite good, especially for profiles nearly coincident in time and space, and during periods of little dynamic activity over the area considered. The percent difference between the ozone column density of the mean balloon and SAGE profile is 4.4 percent (-3.3) percent in the altitude region between 10 and 26 km. From a statistical analysis it appears that there is a small but meaningful difference between the mean profiles at the level of the ozone maximum and around the 30-km level. An error analysis of both data sets give similar results, leading to the conclusion that these differences are instrumentally induced. However, differences between the mean profiles in the lower stratosphere are probably real and due to the high ozone variability in time and space in that altitude region.

Impact of downward-mixing ozone on surface ozone accumulation in southern Taiwan.

PubMed

Lin, Ching-Ho

2008-04-01

The ozone that initially presents in the previous day's afternoon mixing layer can remain in the nighttime atmosphere and then be carried over to the next morning. Finally, this ozone can be brought to the ground by downward mixing as mixing depth increases during the daytime, thereby increasing surface ozone concentrations. Variation of ozone concentration during each of these periods is investigated in this work. First, ozone concentrations existing in the daily early morning atmosphere at the altitude range of the daily maximum mixing depth (residual ozone concentrations) were measured using tethered ozonesondes on 52 experimental days during 2004-2005 in southern Taiwan. Daily downward-mixing ozone concentrations were calculated by a box model coupling the measured daily residual ozone concentrations and daily mixing depth variations. The ozone concentrations upwind in the previous day's afternoon mixing layer were estimated by the combination of back air trajectory analysis and known previous day's surface ozone distributions. Additionally, the relationship between daily downward-mixing ozone concentration and daily photochemically produced ozone concentration was examined. The latter was calculated by removing the former from daily surface maximum ozone concentration. The measured daily residual ozone concentrations distributed at 12-74 parts per billion (ppb) with an average of 42 +/- 17 ppb are well correlated with the previous upwind ozone concentration (R2 = 0.54-0.65). Approximately 60% of the previous upwind ozone was estimated to be carried over to the next morning and became the observed residual ozone. The daily downward-mixing ozone contributes 48 +/- 18% of the daily surface maximum ozone concentration, indicating that the downward-mixing ozone is as important as daily photochemically produced ozone to daily surface maximum ozone accumulation. The daily downward-mixing ozone is poorly correlated with the daily photochemically produced ozone and contributes significantly to the daily variation of surface maximum ozone concentrations (R2 = 0.19). However, the contribution of downward-mixing ozone to daily ozone variation is not included in most existing statistical models developed for predicting daily ozone variation. Finally, daily surface maximum ozone concentration is positively correlated with daily afternoon mixing depth, attributable to the downward-mixing ozone.

On the link between martian total ozone and potential vorticity

NASA Astrophysics Data System (ADS)

Lewis, S.; Holmes, J.; Patel, M.

2016-12-01

We demonstrate for the first time that total ozone in the martian atmosphere is highly correlated with the dynamical tracer, potential vorticity, under certain conditions. The degree of correlation is investigated using a Mars global circulation model including a photochemical model. Potential vorticity is the quantity of choice to explore the dynamical nature of polar vortices because it contains information on winds and temperature in a single scalar variable.The correlation is found to display a distinct seasonal variation, with a strong positive correlation in both northern and southern winter at poleward latitudes in the northern and southern hemisphere respectively. The identified strong correlation implies variations in polar total ozone during winter are predominantly controlled by dynamical processes in these spatio-temporal regions. The weak correlation in northern and southern summer is due to the dominance of photochemical reactions resulting from extended exposure to sunlight. The total ozone/potential vorticity correlation is slightly weaker in southern winter due to topographical variations and the preference for ozone to accumulate in Hellas basin. In northern winter, total ozone can be used to track the polar vortex edge. The ozone/potential vorticity ratio is calculated for both northern and southern winter on Mars for the first time. Using the strong correlation in total ozone and potential vorticity in northern winter inside the polar vortex, it is shown that potential vorticity can be used as a proxy to deduce the distribution of total ozone where satellites cannot observe for the majority of northern winter. Where total ozone observations are available on the fringes of northern winter at poleward latitudes, the strong relationship of total ozone and potential vorticity implies that total ozone anomalies in the surf zone can be of use to investigate the origin of potential vorticity filaments.

On the link between martian total ozone and potential vorticity

NASA Astrophysics Data System (ADS)

Holmes, James A.; Lewis, Stephen R.; Patel, Manish R.

2017-01-01

We demonstrate for the first time that total ozone in the martian atmosphere is highly correlated with the dynamical tracer, potential vorticity, under certain conditions. The degree of correlation is investigated using a Mars global circulation model including a photochemical model. Potential vorticity is the quantity of choice to explore the dynamical nature of polar vortices because it contains information on winds and temperature in a single scalar variable. The correlation is found to display a distinct seasonal variation, with a strong positive correlation in both northern and southern winter at poleward latitudes in the northern and southern hemisphere respectively. The identified strong correlation implies variations in polar total ozone during winter are predominantly controlled by dynamical processes in these spatio-temporal regions. The weak correlation in northern and southern summer is due to the dominance of photochemical reactions resulting from extended exposure to sunlight. The total ozone/potential vorticity correlation is slightly weaker in southern winter due to topographical variations and the preference for ozone to accumulate in Hellas basin. In northern winter, total ozone can be used to track the polar vortex edge. The ozone/potential vorticity ratio is calculated for both northern and southern winter on Mars for the first time. Using the strong correlation in total ozone and potential vorticity in northern winter inside the polar vortex, it is shown that potential vorticity can be used as a proxy to deduce the distribution of total ozone where satellites cannot observe for the majority of northern winter. Where total ozone observations are available on the fringes of northern winter at poleward latitudes, the strong relationship of total ozone and potential vorticity implies that total ozone anomalies in the surf zone of the northern polar vortex can potentially be used to determine the origin of potential vorticity filaments.

Effects of the Bermuda High and the Great Plains low-level jet upon background and peak ozone concentrations in Texas urban areas

NASA Astrophysics Data System (ADS)

Estes, M. J.; Wang, Y.; Lei, R.; Wang, S. C.; Jia, B.

2017-12-01

Previous studies have established that the westward extent of the Bermuda High is strongly linked to the ozone concentrations in Houston. This study examines the linkages between the Bermuda High, the Great Plains low-level jet, background ozone in the eastern half of Texas, and local contributions to peak ozone in Texas urban areas. Analysis of North American Regional Reanalysis (NARR) wind and pressure fields will be used to establish the presence and strength of synoptic-scale weather features, and this information will be used with ozone data from air quality networks to determine the effects upon the seasonal and interannual variations of ozone. Quantification of the effects of large-scale meteorological factors will improve understanding of the causes of ozone variations, including decadal trends in Texas cities.

Naphthenic acids speciation and removal during petroleum-coke adsorption and ozonation of oil sands process-affected water.

PubMed

Gamal El-Din, Mohamed; Fu, Hongjing; Wang, Nan; Chelme-Ayala, Pamela; Pérez-Estrada, Leonidas; Drzewicz, Przemysław; Martin, Jonathan W; Zubot, Warren; Smith, Daniel W

2011-11-01

The Athabasca Oil Sands industry produces large volumes of oil sands process-affected water (OSPW) as a result of bitumen extraction and upgrading processes. Constituents of OSPW include chloride, naphthenic acids (NAs), aromatic hydrocarbons, and trace heavy metals, among other inorganic and organic compounds. To address the environmental issues associated with the recycling and/or safe return of OSPW into the environment, water treatment technologies are required. This study examined, for the first time, the impacts of pretreatment steps, including filtration and petroleum-coke adsorption, on ozonation requirements and performance. The effect of the initial OSPW pH on treatment performance, and the evolution of ozonation and its impact on OSPW toxicity and biodegradability were also examined. The degradation of more than 76% of total acid-extractable organics was achieved using a semi-batch ozonation system at a utilized ozone dose of 150 mg/L. With a utilized ozone dose of 100 mg/L, the treated OSPW became more biodegradable and showed no toxicity towards Vibrio fischeri. Changes in the NA profiles in terms of carbon number and number of rings were observed after ozonation. The filtration of the OSPW did not improve the ozonation performance. Petroleum-coke adsorption was found to be effective in reducing total acid-extractable organics by a 91%, NA content by an 84%, and OSPW toxicity from 4.3 to 1.1 toxicity units. The results of this study indicate that the combination of petroleum-coke adsorption and ozonation is a promising treatment approach to treat OSPW. Copyright © 2011 Elsevier B.V. All rights reserved.

Use of Ozone to Treat Ileostomy Dermatitis in an Experimental Rat Model

PubMed Central

Biçer, Şenol; Sayar, İlyas; Gürsul, Cebrail; Işık, Arda; Aydın, Merve; Peker, Kemal; Demiryilmaz, İsmail

2016-01-01

Background Dermatitis associated with ileostomy is an important problem that affects many people, especially children. The aim of this study was to investigate the therapeutic effects of ozone on dermatitis due to ileostomy, and to develop an alternative treatment option. Material/Methods A total of 28 rats were divided into 4 groups: control, ileostomy, ozone, and zinc oxide. Ileostomy was performed in all rats except the control group. After a 1-week waiting time, the ozone group was administered ozone therapy and the zinc oxide group was administered zinc oxide cream locally once a day for a total of 7 days. All rats were sacrificed at the end of this period. The efficacy of treatment was examined by biochemical, histopathological, and immunohistochemical parameters. The levels of malondialdehyde (MDA), total glutathione (tGSH), total antioxidant capacity (TAC), and total oxidant status (TOS) were measured from tissue. Vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) were examined immunohistochemically. Results Dermatitis occurred pathologically in all rats that underwent ileostomy surgery. The lowest dermatitis score was in the ozone treatment group (p<0.05). Ileostomy dermatitis caused increased levels of MDA and TOS. Ozone treatment resulted in reduced MDA and TOS levels, while the levels of tGSH and TAC were increased (p<0.05). Both VEGF and PCNA immunostaining were augmented in the ozone treatment group (p<0.05). Conclusions Local ozone application may be a good alternative compared to the conventional treatment methods for the prevention of skin lesions that develop after ileostomy. PMID:26947591

Changes in biologically active ultraviolet radiation reaching the Earth's surface.

PubMed

McKenzie, Richard L; Björn, Lars Olof; Bais, Alkiviadis; Ilyasad, Mohammad

2003-01-01

Since publication of the 1998 UNEP Assessment, there has been continued rapid expansion of the literature on UV-B radiation. Many measurements have demonstrated the inverse relationship between column ozone amount and UV radiation, and in a few cases long-term increases due to ozone decreases have been identified. The quantity, quality and availability of ground-based UV measurements relevant to assessing the environmental impacts of ozone changes continue to improve. Recent studies have contributed to delineating regional and temporal differences due to aerosols, clouds, and ozone. Improvements in radiative transfer modelling capability now enable more accurate characterization of clouds, snow-cover, and topographical effects. A standardized scale for reporting UV to the public has gained wide acceptance. There has been increased use of satellite data to estimate geographic variability and trends in UV. Progress has been made in assessing the utility of satellite retrievals of UV radiation by comparison with measurements at the Earth's surface. Global climatologies of UV radiation are now available on the Internet. Anthropogenic aerosols play a more important role in attenuating UV irradiances than has been assumed previously, and this will have implications for the accuracy of UV retrievals from satellite data. Progress has been made inferring historical levels of UV radiation using measurements of ozone (from satellites or from ground-based networks) in conjunction with measurements of total solar radiation obtained from extensive meteorological networks. We cannot yet be sure whether global ozone has reached a minimum. Atmospheric chlorine concentrations are beginning to decrease. However, bromine concentrations are still increasing. While these halogen concentrations remain high, the ozone layer remains vulnerable to further depletion from events such as volcanic eruptions that inject material into the stratosphere. Interactions between global warming and ozone depletion could delay ozone recovery by several years, and this topic remains an area of intense research interest. Future changes in greenhouse gases will affect the future evolution of ozone through chemical, radiative, and dynamic processes In this highly coupled system, an evaluation of the relative importance of these processes is difficult: studies are ongoing. A reliable assessment of these effects on total column ozone is limited by uncertainties in lower stratospheric response to these changes. At several sites, changes in UV differ from those expected from ozone changes alone, possibly as a result of long-term changes in aerosols, snow cover, or clouds. This indicates a possible interaction between climate change and UV radiation. Cloud reflectance measured by satellite has shown a long-term increase at some locations, especially in the Antarctic region, but also in Central Europe, which would tend to reduce the UV radiation. Even with the expected decreases in atmospheric chlorine, it will be several years before the beginning of an ozone recovery can be unambiguously identified at individual locations. Because UV-B is more variable than ozone, any identification of its recovery would be further delayed.

Measurements of Ozone, Lightning, and Electric Fields within Thunderstorms over Langmuir Laboratory, New Mexico

NASA Astrophysics Data System (ADS)

Eack, K. B.; Winn, W. P.; Rust, W. D.; Minschwaner, K.; Fredrickson, S.; Kennedy, D.; Edens, H. E.; Kalnajs, L. E.; Rabin, R. M.; Lu, G. P.; Bonin, D.

2008-12-01

A field project was conducted at the Langmuir Laboratory for Atmospheric Research during the summer of 2008 in an effort to better understand the direct production of ozone within electrically active storms. Five balloon flights were successfully launched into thunderstorms during this project. In situ measurements from the balloon instrument package included ozone mixing ratio, electric field strength, meteorological variables, and GPS location and timing. Lightning discharges were identified within each storm using a ground based lightning mapping array. The data show that the instruments ascended through regions of high electric fields within the sampled storms, and in some cases the balloon was in very close proximity to lightning. Relationships between electric field, lightning, and ozone observed during these flights will be discussed.

Instrument characterization for the detection of long-term changes in stratospheric ozone - An analysis of the SBUV/2 radiometer

NASA Technical Reports Server (NTRS)

Frederick, J. E.; Heath, D. F.; Cebula, R. P.

1986-01-01

The scientific objective of unambiguously detecting subtle global trends in upper stratospheric ozone requires that one maintains a thorough understanding of the satellite-based remote sensors intended for this task. The instrument now in use for long term ozone monitoring is the SBUV/2 being flown on NOAA operational satellites. A critical activity in the data interpretation involves separating small changes in measurement sensitivity from true atmospheric variability. By defining the specific issues that must be addressed and presenting results derived early in the mission of the first SBUV/2 flight model, this work serves as a guide to the instrument investigations that are essential in the attempt to detect long-term changes in the ozone layer.

North Atlantic Oscillation modulates total ozone winter trends

NASA Astrophysics Data System (ADS)

Appenzeller, Christof; Weiss, Andrea K.; Staehelin, Johannes

2000-04-01

The North Atlantic Oscillation (NAO) is modulating the Earth's ozone shield such that the calculated anthropogenic total ozone decrease is enhanced over Europe whereas over the North Atlantic region it is reduced (for the last 30 years). Including the NAO in a statistical model suggests a more uniform chemical winter trend compared to the strong longitudinal variation reported earlier. At Arosa (Switzerland) the trend is reduced to -2.4% per decade compared to -3.2% and at Reykjavik (Iceland) it is enhanced to -3.8% compared to 0%. The revised trend is slightly below the predictions by 2D chemical models. Decadal ozone variability is linked to variations in the dynamical structure of the atmosphere, as reflected in the tropopause pressure. The latter varies in concert with the NAO index with a distinct geographical pattern.

Analysis of air quality with numerical simulation (CMAQ), and observations of trace gases

NASA Astrophysics Data System (ADS)

Castellanos, Patricia

Ozone, a secondary pollutant, is a strong oxidant that can pose a risk to human health. It is formed from a complex set of photochemical reactions involving nitrogen oxides (NOx) and volatile organic compounds (VOCs). Ambient measurements and air quality modeling of ozone and its precursors are important tools for support of regulatory decisions, and analyzing atmospheric chemical and physical processes. I worked on three methods to improve our understanding of photochemical ozone production in the Eastern U.S.: a new detector for NO2, a numerical experiment to test the sensitivity to the timing to emissions, and comparison of modeled and observed vertical profiles of CO and ozone. A small, commercially available cavity ring-down spectroscopy (CRDS) NO2 detector suitable for surface and aircraft monitoring was modified and characterized. The CRDS detector was run in parallel to an ozone chemiluminescence device with photolytic conversion of NO2 to NO. The two instruments measured ambient air in suburban Maryland. A linear least-squares fit to a direct comparison of the data resulted in a slope of 0.960+/-0.002 and R of 0.995, showing agreement between two measurement techniques within experimental uncertainty. The sensitivity of the Community Multiscale Air Quality (CMAQ) model to the temporal variation of four emissions sectors was investigated to understand the effect of emissions' daily variability on modeled ozone. Decreasing the variability of mobile source emissions changed the 8-hour maximum ozone concentration by +/-7 parts per billion by volume (ppbv). Increasing the variability of point source emissions affected ozone concentrations by +/-6 ppbv, but only in areas close to the source. CO is an ideal tracer for analyzing pollutant transport in AQMs because the atmospheric lifetime is longer than the timescale of boundary layer mixing. CO can be used as a tracer if model performance of CO is well understood. An evaluation of CO model performance in CMAQ was carried out using aircraft observations taken for the Regional Atmospheric Measurement, Modeling and Prediction Program (RAMMPP) in the summer of 2002. Comparison of modeled and observed CO total columns were generally in agreement within 5-10%. There is little evidence that the CO emissions inventory is grossly overestimated. CMAQ predicts the same vertical profile shape for all of the observations, i.e. CO is well mixed throughout the boundary layer. However, the majority of observations have poorly mixed air below 500 m, and well mixed air above. CMAQ appears to be transporting CO away from the surface more quickly than what is observed. Turbulent mixing in the model is represented with K-theory. A minimum Kz that scales with fractional urban land use is imposed in order to account for subgrid scale obstacles in urban areas and the urban heat island effect. Micrometeorological observations suggest that the minimum Kz is somewhat high. A sensitivity case where the minimum K z was reduced from 0.5 m2/s to 0.1 m2/s was carried out. Model performance of surface ozone observations at night increased significantly. The model better captures the observed ozone minimum with slower mixing, and increases ozone concentrations in the residual layer. Model performance of CO and ozone morning vertical profiles improves, but the effect is not large enough to bring the model and measurements into agreement. Comparison of modeled CO and O3 vertical profiles shows that turbulent mixing (as represented by eddy diffusivity) appears to be too fast, while convective mixing may be too slow.

Kinetics of p-hydroxybenzoic acid photodecomposition and ozonation in a batch reactor.

PubMed

Benitez, F J; Beltran-Heredia, J; Peres, J A; Dominguez, J R

2000-04-03

The decomposition of p-hydroxybenzoic acid, an important pollutant present in the wastewaters of the olive oil industry, has been carried out by a direct photolysis provided by a polychromatic UV radiation source, and by ozone. In both processes, the conversions obtained as a function of the operating variables (temperature, pH and ozone partial pressure in the ozonation process) are reported. In order to evaluate the radiation flow rate absorbed by the solutions in the photochemical process, the Line Source Spherical Emission Model is used. The application of this model to the experimental results provides the determination of the reaction quantum yields which values ranged between 8.62 and 81.43 l/einstein. In the ozonation process, the film theory allows to establish that the absorption process takes place in the fast and pseudo-first-order regime and the reaction is overall second-order, first-order with respect to both reactants, ozone and p-hydroxybenzoic acid. The rate constants are evaluated and vary between 0.18x10(5) and 29.9x10(5) l/mol s depending on the temperature and pH.

An Extended View of Mars Ozone

NASA Technical Reports Server (NTRS)

Fast, Kelly

2011-01-01

We present an ongoing effort to characterize chemistry in Mars' atmosphere in multiple seasons on timescales longer than flight missions through coordinated efforts by GSFC's HIPWAC spectrometer and Mars Express SPICAM, archival measurements, and tests/application of photochemical models. The trace species ozone (O3) is an effective probe of atmospheric chemistry because it is destroyed by chemically active odd hydrogen species (HO(sub x)) that result from water vapor photolysis. Observed ozone abundance on Mars is a critical test for three-dimensional photochemistry coupled general circulation models (GCM) that make specific predictions for the spatial, diurnal, and seasonal behavior of ozone and related chemistry and climatological conditions. Coordinated measurements by HIPWAC and SPICAM quantitatively linked mission data to the 23-year GSFC ozone data record and also revealed unanticipated inter-decadal variability of same-season ozone abundances, a possible indicator of changing cloud activity (heterogeneous sink for HO(sub x)). A detailed study of long-term conditions is critical to characterizing the predictability of Mars' seasonal chemical behavior, particularly in light of the implications of and the lack of explanation for reported methane behavior.

Field responses of Prunus serotina and Asclepias syriaca to ozone around southern Lake Michigan.

PubMed

Bennett, J P; Jepsen, E A; Roth, J A

2006-07-01

Higher ozone concentrations east of southern Lake Michigan compared to west of the lake were used to test hypotheses about injury and growth effects on two plant species. We measured approximately 1000 black cherry trees and over 3000 milkweed stems from 1999 to 2001 for this purpose. Black cherry branch elongation and milkweed growth and pod formation were significantly higher west of Lake Michigan while ozone injury was greater east of Lake Michigan. Using classification and regression tree (CART) analyses we determined that departures from normal precipitation, soil nitrogen and ozone exposure/peak hourly concentrations were the most important variables affecting cherry branch elongation, and milkweed stem height and pod formation. The effects of ozone were not consistently comparable with the effects of soil nutrients, weather, insect or disease injury, and depended on species. Ozone SUM06 exposures greater than 13 ppm-h decreased cherry branch elongation 18%; peak 1-h exposures greater than 93 ppb reduced milkweed stem height 13%; and peak 1-h concentrations greater than 98 ppb reduced pod formation 11% in milkweed.

Development of an Aura Chemical Reanalysis in support Air Quality Applications

NASA Astrophysics Data System (ADS)

Pierce, R. B.; Lenzen, A.; Schaack, T.

2015-12-01

We present results of chemical data assimilation experiments utilizing the NOAA National Environmental Satellite, Data, and Information Service (NESDIS), University of Wisconsin Space Science and Engineering (SSEC) Real-time Air Quality Modeling System (RAQMS) in conjunction with the NOAA National Centers for Environmental Prediction (NCEP) Operational Gridpoint Statistical Interpolation (GSI) 3-dimensional variational data assimilation system. The impact of assimilating NASA Ozone Monitoring Instrument (OMI) total column ozone, OMI tropospheric nitrogen dioxide columns, and Microwave Limb Sounder (MLS) stratospheric ozone profiles on background ozone is assessed using measurements from the 2010 NSF High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observation (HIPPO) and NOAA California Nexus (CalNex) campaigns. Results show that the RAQMS/GSI Chemical Reanalysis is able to provide very good estimates of background ozone and large-scale ozone variability and is suitable for use in constraining regional air quality modeling activities. These experiments are being used to guide the development of a multi-year global chemical and aerosol reanalysis using NASA Aura and A-Train measurements to support air quality applications.

Solar or UVA-Visible Photocatalytic Ozonation of Water Contaminants.

PubMed

Beltrán, Fernando J; Rey, Ana

2017-07-14

An incipient advanced oxidation process, solar photocatalytic ozonation (SPO), is reviewed in this paper with the aim of clarifying the importance of this process as a more sustainable water technology to remove priority or emerging contaminants from water. The synergism between ozonation and photocatalytic oxidation is well known to increase the oxidation rate of water contaminants, but this has mainly been studied in photocatalytic ozonation systems with lamps of different radiation wavelength, especially of ultraviolet nature (UVC, UVB, UVA). Nowadays, process sustainability is critical in environmental technologies including water treatment and reuse; the application of SPO systems falls into this category, and contributes to saving energy and water. In this review, we summarized works published on photocatalytic ozonation where the radiation source is the Sun or simulated solar light, specifically, lamps emitting radiation to cover the UVA and visible light spectra. The main aspects of the review include photoreactors used and radiation sources applied, synthesis and characterization of catalysts applied, influence of main process variables (ozone, catalyst, and pollutant concentrations, light intensity), type of water, biodegradability and ecotoxicity, mechanism and kinetics, and finally catalyst activity and stability.

Evaluation of Day and Nighttime Lower Tropospheric Ozone from Air Quality Models using TES and Ozonesondes

NASA Astrophysics Data System (ADS)

Osterman, G. B.; Neu, J. L.; Eldering, A.; Pinder, R. W.; Tang, Y.; McQueen, J.

2012-12-01

At night, ozone can be transported long distances above the surface inversion layer without chemical destruction or deposition. As the boundary layer breaks up in the morning, this nocturnal ozone can be mixed down to the surface and rapidly increase ozone concentrations at a rate that can rival chemical ozone production. Most regional scale models that are used for air quality forecasts and ozone source attribution do not adequately capture nighttime ozone concentrations and transport. We combine ozone profile data from the NASA Earth Observing System (EOS) Tropospheric Emission Spectrometer (TES) and other sensors, ozonesonde data collected during the INTEX Ozonesonde Network Study (IONS), EPA AirNow ground station ozone data, the Community Multi-Scale Air Quality (CMAQ) model, and the National Air Quality Forecast Capability (NAQFC) model to examine air quality events during August 2006. We present both aggregated statistics and case-study analyses that assess the relationship between the models' ability to reproduce surface air quality events and their ability to capture the vertical distribution of ozone both during the day and at night. We perform the comparisons looking at the geospatial dependence in the differences between the measurements and models under different surface ozone conditions.

Seasonal Variability of Middle Latitude Ozone in the Lowermost Stratosphere Derived from Probability Distribution Functions

NASA Technical Reports Server (NTRS)

Rood, Richard B.; Douglass, Anne R.; Cerniglia, Mark C.; Sparling, Lynn C.; Nielsen, J. Eric

1999-01-01

We present a study of the distribution of ozone in the lowermost stratosphere with the goal of characterizing the observed variability. The air in the lowermost stratosphere is divided into two population groups based on Ertel's potential vorticity at 300 hPa. High (low) potential vorticity at 300 hPa indicates that the tropopause is low (high), and the identification of these two groups is made to account for the dynamic variability. Conditional probability distribution functions are used to define the statistics of the ozone distribution from both observations and a three-dimensional model simulation using winds from the Goddard Earth Observing System Data Assimilation System for transport. Ozone data sets include ozonesonde observations from northern midlatitude stations (1991-96) and midlatitude observations made by the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) (1994- 1998). The conditional probability distribution functions are calculated at a series of potential temperature surfaces spanning the domain from the midlatitude tropopause to surfaces higher than the mean tropical tropopause (approximately 380K). The probability distribution functions are similar for the two data sources, despite differences in horizontal and vertical resolution and spatial and temporal sampling. Comparisons with the model demonstrate that the model maintains a mix of air in the lowermost stratosphere similar to the observations. The model also simulates a realistic annual cycle. Results show that during summer, much of the observed variability is explained by the height of the tropopause. During the winter and spring, when the tropopause fluctuations are larger, less of the variability is explained by tropopause height. This suggests that more mixing occurs during these seasons. During all seasons, there is a transition zone near the tropopause that contains air characteristic of both the troposphere and the stratosphere. The relevance of the results to the assessment of the environmental impact of aircraft effluence is also discussed.

Correlation of DIAL Ozone Observations with Lightning

NASA Technical Reports Server (NTRS)

Peterson, Harold; Kuang, Shi; Koshak, William; Newchurch, Michael

2014-01-01

The purpose of this project is to see whether ozone maxima measured by the DIfferential Absorption Lidar (DIAL) instrument in Huntsville, AL may be traced back to lightning events occurring 24-48 hours beforehand. The methodology is to start with lidar measurements of ozone from DIAL. The HYbrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model is then used to determine the origin of these ozone maxima 24-48 hours prior. Data from the National Lightning Detection Network (NLDN) are used to examine the presence/absence of lightning along the trajectory. This type of analysis suggests that lightning-produced NOx may be responsible for some of the ozone maxima over Huntsville.

Monitoring of Observation Errors in the Assimilation of Satellite Ozone Data

NASA Technical Reports Server (NTRS)

Stajner, Ivanka; Winslow, Nathan; Rood, Richard B.; Pawson, Steven

2003-01-01

The stratospheric ozone layer protects life on Earth from the harmful effects of solar ultravioiet radiation. The ozone layer is currently in a fragile state because of depletion caused by man-made chemicals, especially chlorofluorocarbons. The state of the ozone layer is being monitored and evaluated by scientific experts around the world, in order to help policy makers assess the impacts of international protocols that control the production and release of ozone depleting chemicals. Scientists use a variety ozone measurements and models in order to form a comprehensive picture about the current state of the ozone layer, and to predict the future behavior (expected to be a recovery, as the abundance of the depleting chemicals decreases). Among the data sets used, those from satellite-borne instruments have the advantage of providing a wealth of information about the ozone distribution over most of the globe. Several instruments onboard American and international satellites make measurements of the properties of the atmosphere, from which atmospheric ozone amounts are estimated; long-term measurement programs enable monitoring of trends in ozone. However, the characteristics of satellite instruments change in time. For example, the instrument lenses through which measurements are made may deteriorate over time, or the satellite orbit may drift so that measurements over each location are made later and later in the day. These changes may increase the errors in the retrieved ozone amounts, and degrade the quality of estimated ozone amounts and of their variability. Our work focuses on combining the satellite ozone data with global models that capture atmospheric motion and ozone chemistry, using advanced statistical techniques: this is known as data assimilation. Our method provides a three-dimensional global ozone distribution that is consistent with both the satellite measurements and with our understanding of processes (described in the models) that control ozone distribution. Through the monitoring of statistical properties of the agreement between the data and the model, this approach also enables us to detect changes in the quality of ozone data retrieved from satellite-borne instrument measurements. This paper demonstrates that calculations of the changes in satellite data quality, and the impact these changes on the estimates of the global ozone distribution, can assist in maintaining the uniform quality of the satellite ozone data throughout the lifetime of these instruments, thus contributing to our understanding of long-term ozone change.

Effects of ozone (O3) therapy on cisplatin-induced ototoxicity in rats.

PubMed

Koçak, Hasan Emre; Taşkın, Ümit; Aydın, Salih; Oktay, Mehmet Faruk; Altınay, Serdar; Çelik, Duygu Sultan; Yücebaş, Kadir; Altaş, Bengül

2016-12-01

The aim of this study is to investigate the effect of rectal ozone and intratympanic ozone therapy on cisplatin-induced ototoxicity in rats. Eighteen female Wistar albino rats were included in our study. External auditory canal and tympanic membrane examinations were normal in all rats. The rats were randomly divided into three groups. Initially, all the rats were tested with distortion product otoacoustic emissions (DPOAE), and emissions were measured normally. All rats were injected with 5-mg/kg/day cisplatin for 3 days intraperitoneally. Ototoxicy had developed in all rats, as confirmed with DPOAE after 1 week. Rectal and intratympanic ozone therapy group was Group 1. No treatment was administered for the rats in Group 2 as the control group. The rats in Group 3 were treated with rectal ozone. All the rats were tested with DPOAE under general anesthesia, and all were sacrificed for pathological examination 1 week after ozone administration. Their cochleas were removed. The outer hair cell damage and stria vascularis damage were examined. In the statistical analysis conducted, a statistically significant difference between Group 1 and Group 2 was observed in all frequencies according to the DPOAE test. In addition, between Group 2 and Group 3, a statistically significant difference was observed in the DPOAE test. However, a statistically significant difference was not observed between Group 1 and Group 3 according to the DPOAE test. According to histopathological scoring, the outer hair cell damage score was statistically significantly high in Group 2 compared with Group 1. In addition, the outer hair cell damage score was also statistically significantly high in Group 2 compared with Group 3. Outer hair cell damage scores were low in Group 1 and Group 3, but there was no statistically significant difference between these groups. There was no statistically significant difference between the groups in terms of stria vascularis damage score examinations. Systemic ozone gas therapy is effective in the treatment of cell damage in cisplatin-induced ototoxicity. The intratympanic administration of ozone gas does not have any additional advantage over the rectal administration.

EFFECT OF RAPID SHALLOW BREATHING ON THE DISTRIBUTION OF 18-O-LABELED OZONE REACTION PRODUCT IN THE RESPIRATORY TRACT OF THE RAT

EPA Science Inventory

We examined the effect of breathing pattern on ozone reaction product content within the respiratory tract. Thirty-four anesthetized, maleWistar rats were exposed to oxygen-18 (18O)-labeled ozone at 1.0 ppm for 2 h using a dual-chamber, negative-pressure ventilation system. Fre...

Ozone air pollution and foliar injury development on native plants of Switzerland.

PubMed

Novak, Kristopher; Skelly, John M; Schaub, Marcus; Kräuchi, Norbert; Hug, Christian; Landolt, Werner; Bleuler, Peter

2003-01-01

The objectives of this study were to examine the foliar sensitivity to ozone exposure of 12 tree, shrub, and herbaceous species native to southern Switzerland and determine the seasonal cumulative ozone exposures required to induce visible foliar injury. The study was conducted from the beginning of May through the end of August during 2000 and 2001 using an open-top chamber research facility located within the Lattecaldo Cantonal Forest Nursery in Canton Ticino, southern Switzerland (600 m asl). Plants were examined daily and dates of initial foliar injury were recorded in order to determine the cumulative AOT40 ppb h ozone exposure required to cause visible foliar injury. Plant responses to ozone varied significantly among species; 11 species exhibited visible symptoms typical of exposures to ambient ozone. The symptomatic species (from most to least sensitive) were Populus nigra, Viburnum lantana, Salix alba, Crataegus monogyna, Viburnum opulus, Tilia platyphyllos, Cornus alba, Prunus avium, Fraxinus excelsior, Ribes alpinum, and Tilia cordata; Clematis spp. did not show foliar symptoms. Of the 11 symptomatic species, five showed initial injury below the critical level AOT40 10 ppmh O3 in the 2001 season.

Polar Processes in a 50-year Simulation of Stratospheric Chemistry and Transport

NASA Technical Reports Server (NTRS)

Kawa, S.R.; Douglass, A. R.; Patrick, L. C.; Allen, D. R.; Randall, C. E.

2004-01-01

The unique chemical, dynamical, and microphysical processes that occur in the winter polar lower stratosphere are expected to interact strongly with changing climate and trace gas abundances. Significant changes in ozone have been observed and prediction of future ozone and climate interactions depends on modeling these processes successfully. We have conducted an off-line model simulation of the stratosphere for trace gas conditions representative of 1975-2025 using meteorology from the NASA finite-volume general circulation model. The objective of this simulation is to examine the sensitivity of stratospheric ozone and chemical change to varying meteorology and trace gas inputs. This presentation will examine the dependence of ozone and related processes in polar regions on the climatological and trace gas changes in the model. The model past performance is base-lined against available observations, and a future ozone recovery scenario is forecast. Overall the model ozone simulation is quite realistic, but initial analysis of the detailed evolution of some observable processes suggests systematic shortcomings in our description of the polar chemical rates and/or mechanisms. Model sensitivities, strengths, and weaknesses will be discussed with implications for uncertainty and confidence in coupled climate chemistry predictions.

Scientific Studies in Association with the Halogen Occultation Experiment

NASA Technical Reports Server (NTRS)

Mickley, Lorretta J.; Frederick, John E.

1996-01-01

This work examines measurements of ozone, NO, NO2, and HCl made by the Halogen Occultation Experiment (HALOE) to track chemical change in the stratosphere. In addition, HALOE observations of two long-lived species, HF and CH4, are used as tracers to distinguish between change due to transport processes and change due to chemistry. The first study investigates the response of NO(x), (NO and NO2) and ozone to the presence of large amounts of sulfate aerosol in the stratosphere following the 1991 eruption of Mount Pinatubo. As the Pinatubo aerosol cleared the atmosphere at 17 mb (about 27-28 km), the partitioning of total reactive nitrogen shifted more toward NO(x), and ozone amounts declined. This trend is opposite that observed at lower altitudes. The second study examines the chemical aftermath of severe ozone depletion over Antarctica in spring. When ozone levels drop to a threshold amount (about 1 ppm near 20 km), the partitioning of the total chlorine family shifts rapidly from reactive species to the reservoir molecule HCl. This sudden repartitioning shuts down further ozone loss and may be significant as filaments of air peel off the polar vortex and mix with mid-latitude air.

Stratospheric Instrusion Catalog: A 10-Year Compilation of Events Identified by using TRACK with NASA's MERRA-2 Reanalysis

NASA Technical Reports Server (NTRS)

Knowland, K. Emma; Ott, Lesley E.; Duncan, Bryan N.; Wargan, Kris; Hodges, Kevin

2017-01-01

Stratospheric intrusions "the introduction of ozone-rich stratospheric air into the troposphere" have been linked with surface ozone air quality exceedances, especially at the high elevations in the western USA in springtime. However, the impact of stratospheric intrusions in the remaining seasons and over the rest of the USA is less clear. A new approach to the study of stratospheric intrusions uses NASA's Goddard Earth Observing System Model (GEOS) model and assimilation products with an objective feature tracking algorithm to investigate the atmospheric dynamics that generate stratospheric intrusions and the different mechanisms through which stratospheric intrusions may influence tropospheric chemistry and surface air quality seasonally over both the western and the eastern USA. A catalog of stratospheric intrusions identified in the MERRA-2 reanalysis was produced for the period 2004-2015 and validated against surface ozone observations (focusing on those which exceed the national air quality standard) and a recent data set of stratospheric intrusion-influenced air quality exceedance flags from the US Environmental Protection Agency (EPA). Considering not all ozone exceedances have been flagged by the EPA, a collection of stratospheric intrusions can support air quality agencies for more rapid identification of the impact of stratospheric air on surface ozone and demonstrates that future operational analyses may aid in forecasting such events. An analysis of the spatiotemporal variability of stratospheric intrusions over the continental US was performed, and while the spring over the western USA does exhibit the largest number of stratospheric intrusions affecting the lower troposphere, the number of intrusions in the remaining seasons and over the eastern USA is sizable. By focusing on the major modes of variability that influence weather in the USA, such as the Pacific North American (PNA) teleconnection index, predicative meteorological patterns associated with stratospheric intrusions and their regional effects on tropospheric ozone were identified. Improved understanding of the connections between large-scale climate variability and local-scale dynamically-driven air quality events may support improved seasonal prediction of such events.

Stratospheric Intrusion Catalog: A 10-year Compilation of Events Identified By Using an Objective Feature Tracking Model With NASA's MERRA-2 Reanalysis

NASA Astrophysics Data System (ADS)

Knowland, K. E.; Ott, L. E.; Duncan, B. N.; Wargan, K.; Hodges, K.

2017-12-01

Stratospheric intrusions - the introduction of ozone-rich stratospheric air into the troposphere - have been linked with surface ozone air quality exceedances, especially at the high elevations in the western USA in springtime. However, the impact of stratospheric intrusions in the remaining seasons and over the rest of the USA is less clear. A new approach to the study of stratospheric intrusions uses NASA's Goddard Earth Observing System Model (GEOS) model and assimilation products with an objective feature tracking algorithm to investigate the atmospheric dynamics that generate stratospheric intrusions and the different mechanisms through which stratospheric intrusions may influence tropospheric chemistry and surface air quality seasonally over both the western and the eastern USA. A catalog of stratospheric intrusions identified in the MERRA-2 reanalysis was produced for the period 2005-2014 and validated against surface ozone observations (focusing on those which exceed the national air quality standard) and a recent data set of stratospheric intrusion-influenced air quality exceedance flags from the US Environmental Protection Agency (EPA). Considering not all ozone exceedances have been flagged by the EPA, a collection of stratospheric intrusions can support air quality agencies for more rapid identification of the impact of stratospheric air on surface ozone and demonstrates that future operational analyses may aid in forecasting such events. An analysis of the spatiotemporal variability of stratospheric intrusions over the continental US was performed, and while the spring over the western USA does exhibit the largest number of stratospheric intrusions affecting the lower troposphere, the number of intrusions in the remaining seasons and over the eastern USA is sizable. By focusing on the major modes of variability that influence weather in the USA, such as the Pacific North American (PNA) teleconnection index, predicative meteorological patterns associated with stratospheric intrusions and their regional effects on tropospheric ozone were identified. Improved understanding of the connections between large-scale climate variability and local-scale dynamically-driven air quality events may support improved seasonal prediction of such events.

Modeling of bromate formation by ozonation of surface waters in drinking water treatment.

PubMed

Legube, Bernard; Parinet, Bernard; Gelinet, Karine; Berne, Florence; Croue, Jean-Philippe

2004-04-01

The main objective of this paper is to try to develop statistically and chemically rational models for bromate formation by ozonation of clarified surface waters. The results presented here show that bromate formation by ozonation of natural waters in drinking water treatment is directly proportional to the "Ct" value ("Ctau" in this study). Moreover, this proportionality strongly depends on many parameters: increasing of pH, temperature and bromide level leading to an increase of bromate formation; ammonia and dissolved organic carbon concentrations causing a reverse effect. Taking into account limitation of theoretical modeling, we proposed to predict bromate formation by stochastic simulations (multi-linear regression and artificial neural networks methods) from 40 experiments (BrO(3)(-) vs. "Ctau") carried out with three sand filtered waters sampled on three different waterworks. With seven selected variables we used a simple architecture of neural networks, optimized by "neural connection" of SPSS Inc./Recognition Inc. The bromate modeling by artificial neural networks gives better result than multi-linear regression. The artificial neural networks model allowed us classifying variables by decreasing order of influence (for the studied cases in our variables scale): "Ctau", [N-NH(4)(+)], [Br(-)], pH, temperature, DOC, alkalinity.

Characterization of the Spatial Variability of Methane, Ozone, and Carbon Dioxide in Two Oil and Gas Production Basins Via a Spatial Grid of Continuous Measurements

NASA Astrophysics Data System (ADS)

Casey, J. G.; Collier, A. M.; Hannigan, M.; Piedrahita, R.; Vaughn, B. H.; Sherwood, O.

2015-12-01

In recent years, aided by the advent of horizontal drilling used in conjunction with hydraulic fracturing, oil and gas production in basins around the United States has increased significantly. A study was conducted in two oil and gas basins during the spring and summer of 2015 to investigate the spatial and temporal variability of several atmospheric trace gases that can be influenced by oil and gas extraction including methane, ozone, and carbon dioxide. Fifteen air quality monitors were distributed across the Denver Julesburg Basin in Northeast Colorado, and the San Juan Basin, which stretches from Southwest Colorado into Northwest New Mexico in Four Corners Region. Spatial variability in ozone was observed across each basin. The presence of dynamic short-term trends observed in the mole fraction of methane and carbon dioxide indicate the extent to which each site is uniquely impacted by local emission sources. Diurnal trends of these two constituents lead toward a better understanding of local pooling of emissions that can be influenced by topography, the planetary boundary layer height, atmospheric stability, as well as the composition and flux of local and regional emissions sources.

Tropical pacing of Antarctic sea ice increase

NASA Astrophysics Data System (ADS)

Schneider, D. P.

2015-12-01

One reason why coupled climate model simulations generally do not reproduce the observed increase in Antarctic sea ice extent may be that their internally generated climate variability does not sync with the observed phases of phenomena like the Pacific Decadal Oscillation (PDO) and ENSO. For example, it is unlikely for a free-running coupled model simulation to capture the shift of the PDO from its positive to negative phase during 1998, and the subsequent ~15 year duration of the negative PDO phase. In previously presented work based on atmospheric models forced by observed tropical SSTs and stratospheric ozone, we demonstrated that tropical variability is key to explaining the wind trends over the Southern Ocean during the past ~35 years, particularly in the Ross, Amundsen and Bellingshausen Seas, the regions of the largest trends in sea ice extent and ice season duration. Here, we extend this idea to coupled model simulations with the Community Earth System Model (CESM) in which the evolution of SST anomalies in the central and eastern tropical Pacific is constrained to match the observations. This ensemble of 10 "tropical pacemaker" simulations shows a more realistic evolution of Antarctic sea ice anomalies than does its unconstrained counterpart, the CESM Large Ensemble (both sets of runs include stratospheric ozone depletion and other time-dependent radiative forcings). In particular, the pacemaker runs show that increased sea ice in the eastern Ross Sea is associated with a deeper Amundsen Sea Low (ASL) and stronger westerlies over the south Pacific. These circulation patterns in turn are linked with the negative phase of the PDO, characterized by negative SST anomalies in the central and eastern Pacific. The timing of tropical decadal variability with respect to ozone depletion further suggests a strong role for tropical variability in the recent acceleration of the Antarctic sea ice trend, as ozone depletion stabilized by late 1990s, prior to the most recent major shift in tropical climate. In the pacemaker runs, the positive sea ice trend in the eastern Ross Sea is stronger during the most recent period (~2000-2014) than it is during period of rapid ozone depletion (~1980-1996).

Distribution and urban-suburban differences in ground-level ozone and its precursors over Shenyang, China

NASA Astrophysics Data System (ADS)

Liu, Ningwei; Ren, Wanhui; Li, Xiaolan; Ma, Xiaogang; Zhang, Yunhai; Li, Bingkun

2018-03-01

Hourly mixing ratio data of ground-level ozone and its main precursors at ambient air quality monitoring sites in Shenyang during 2013-2015 were used to survey spatiotemporal variations in ozone. Then, the transport of ozone and its precursors among urban, suburban, and rural sites was examined. The correlations between ozone and some key meteorological factors were also investigated. Ozone and O x mixing ratios in Shenyang were higher during warm seasons and lower during cold ones, while ozone precursors followed the opposite cycle. Ozone mixing ratios reached maximum and minimum values in the afternoon and morning, respectively, reflecting the significant influence of photochemical production during daytime and depletion via titration during nighttime. Compared to those in downtown Shenyang, ozone mixing ratios were higher and the occurrence of peak values were later in suburban and rural areas downwind of the prevailing wind. The differences were most significant in summer, when the ozone mixing ratios at one suburban downwind site reached a maximum value of 35.6 ppb higher than those at the downtown site. This suggests that photochemical production processes were significant during the transport of ozone precursors, particularly in warm seasons with sufficient sunlight. Temperature, total radiation, and wind speed all displayed positive correlations with ozone concentration, reflecting their important role in accelerating ozone formation. Generally, the correlations between ozone and meteorological factors were slightly stronger at suburban sites than in urban areas, indicating that ozone levels in suburban areas were more sensitive to these meteorological factors.

Can we use the ozone response in a CCM to say which solar spectral irradiance is most likely correct?

NASA Astrophysics Data System (ADS)

Ball, William; Rozanov, Eugene; Shapiro, Anna

2015-04-01

Ozone plays a key role in the temperature structure of the Earth's atmosphere and absorbs damaging ultraviolet (UV) solar radiation. Evidence suggests that variations in stratospheric ozone resulting from changes in solar UV output may have an important role to play in weather over the North Atlantic and Europe on decadal timescales through a "top-down" coupling with the troposphere. However, the magnitude of the stratospheric response to the Sun over the 11-year solar cycle (SC) depends primarily on how much the UV changes. SC UV changes differ significantly between different observational instruments and the observations and models. The substantial disagreements between existing SSI datasets lead to different atmospheric responses when they are used in climate models and, therefore, we still cannot fully understand and simulate the ozone variability. We use the SOCOL chemistry-climate model, in specified dynamics mode, to calculate the atmospheric response from using different spectral irradiance from the SATIRE-S and NRLSSI models and with SORCE observations and a constant Sun. We compare the ozone and hydroxl results from these runs with observations to try to determine which SSI dataset is most likely to be correct. This is important to get a better understanding of which SSI dataset should be used in climate modelling and what magnitude of UV variability the Sun has. This will lead to a better understanding of the Sun's influence upon our climate and weather.

Temporal Variability of Total Ozone in the Asian Region Inferred from Ground-Based and Satellite Measurement Data

NASA Astrophysics Data System (ADS)

Visheratin, K. N.; Nerushev, A. F.; Orozaliev, M. D.; Zheng, Xiangdong; Sun, Shumen; Liu, Li

2017-12-01

This paper reports investigation data on the temporal variability of total ozone content (TOC) in the Central Asian and Tibet Plateau mountain regions obtained by conventional methods, as well as by spectral, cross-wavelet, and composite analyses. The data of ground-based observation stations located at Huang He, Kunming, and Lake Issyk-Kul, along with the satellite data obtained at SBUV/SBUV2 (SBUV merged total and profile ozone data, Version 8.6) for 1980-2013 and OMI (Ozone Monitoring Instrument) and TOU (Total Ozone Unit) for 2009-2013 have been used. The average relative deviation from the SBUV/SBUV2 data is less than 1% in Kunming and Issyk-Kul for the period of 1980-2013, while the Huang He Station is characterized by an excess of the satellite data over the ground-based information at an average deviation of 2%. According to the Fourier analysis results, the distribution of amplitudes and the periods of TOC oscillations within a range of over 14 months is similar for all series analyzed. Meanwhile, according to the cross-wavelet and composite analyses results, the phase relationships between the series may considerably differ, especially in the periods of 5-7 years. The phase of quasi-decennial oscillations in the Kunming Station is close to the 11-year oscillations of the solar cycle, while in the Huang He and Issyk-Kul stations the TOC variations go ahead of the solar cycle.

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) methods are used to quantify ozone transport and photochemical production. On low ozone days, both the IPM and PB methods indicate ozone entrainment is ˜3--4 ppbv·hr-1 in this low photochemical environment of ˜1--4 ppbv·hr-1. During the rapid early morning ozone rise on exceedance days, RL entrainment and photochemical ozone production rates are 5--10 and 10--15 ppbv·hr -1, respectively.

Antarctic ozone loss in 1989-2010: evidence for ozone recovery?

NASA Astrophysics Data System (ADS)

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

2012-04-01

We present a detailed estimation of chemical ozone loss in the Antarctic polar vortex from 1989 to 2010. The analyses include ozone loss estimates for 12 Antarctic ground-based (GB) stations. All GB observations show minimum ozone in the late September-early October period. Among the stations, the lowest minimum ozone values are observed at South Pole and the highest at Dumont d'Urville. The ozone loss starts by mid-June at the vortex edge and then progresses towards the vortex core with time. The loss intensifies in August-September, peaks by the end of September-early October, and recovers thereafter. The average ozone loss in the Antarctic is revealed to be about 33-50% in 1989-1992 in agreement with the increase in halogens during this period, and then stayed at around 48% due to saturation of the loss. The ozone loss in the warmer winters (e.g. 2002, and 2004) is lower (37-46%) and in the colder winters (e.g. 2003, and 2006) is higher (52-55%). Because of small inter-annual variability, the correlation between ozone loss and the volume of polar stratospheric clouds yields ~0.51. The GB ozone and ozone loss values are in good agreement with those found from the space-based observations of the Total Ozone Mapping Spectrometer/Ozone Monitoring Instrument (TOMS/OMI), the Global Ozone Monitoring Experiment (GOME), the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), and the Aura Microwave Limb Sounder (MLS), where the differences are within ±5% and are mostly within the error bars of the measurements. The piece-wise linear trends computed from the September-November vortex average GB and TOMS/OMI ozone show about -4 to -5.6 DU (Dobson Unit) yr-1 in 1989-1996 and about +1 DU yr-1 in 1997-2010. The trend during the former period is significant at 95% confidence intervals, but the trend in 1997-2010 is significant only at 85% confidence intervals. Our analyses suggest a period of about 9-10 yr to get the first detectable ozone recovery signal at the 95% confidence intervals with the current ozone trends in the Antarctic. Thus, this study reveals that the recovery of the Antarctic ozone is well on course.

Stratospheric ozone measurements at Arosa (Switzerland): history and scientific relevance

NASA Astrophysics Data System (ADS)

Staehelin, Johannes; Viatte, Pierre; Stübi, Rene; Tummon, Fiona; Peter, Thomas

2018-05-01

Climatic Observatory (LKO) in Arosa (Switzerland), marking the beginning of the world's longest series of total (or column) ozone measurements. They were driven by the recognition that atmospheric ozone is important for human health, as well as by scientific curiosity about what was, at the time, an ill characterised atmospheric trace gas. From around the mid-1950s to the beginning of the 1970s studies of high atmosphere circulation patterns that could improve weather forecasting was justification for studying stratospheric ozone. In the mid-1970s, a paradigm shift occurred when it became clear that the damaging effects of anthropogenic ozone-depleting substances (ODSs), such as long-lived chlorofluorocarbons, needed to be documented. This justified continuing the ground-based measurements of stratospheric ozone. Levels of ODSs peaked around the mid-1990s as a result of a global environmental policy to protect the ozone layer, implemented through the 1987 Montreal Protocol and its subsequent amendments and adjustments. Consequently, chemical destruction of stratospheric ozone started to slow around the mid-1990s. To some extent, this raises the question as to whether continued ozone observation is indeed necessary. In the last decade there has been a tendency to reduce the costs associated with making ozone measurements globally including at Arosa. However, the large natural variability in ozone on diurnal, seasonal, and interannual scales complicates the capacity for demonstrating the success of the Montreal Protocol. Chemistry-climate models also predict a super-recovery of the ozone layer at mid-latitudes in the second half of this century, i.e. an increase of ozone concentrations beyond pre-1970 levels, as a consequence of ongoing climate change. These factors, and identifying potentially unexpected stratospheric responses to climate change, support the continued need to document stratospheric ozone changes. This is particularly valuable at the Arosa site, due to the unique length of the observational record. This paper presents the evolution of the ozone layer, the history of international ozone research, and discusses the justification for the measurements in the past, present and into future.

A numerical study of tropospheric ozone in the springtime in East Asia

NASA Astrophysics Data System (ADS)

Zhang, Meigen; Xu, Yongfu; Itsushi, Uno; Hajime, Akimoto

2004-04-01

The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tropospheric ozone in March 1998. The calculated mixing ratios of ozone and carbon monoxide are compared with ground level observations at three remote sites in Japan and it is found that the model reproduces the observed features very well. Examination of several high episodes of ozone and carbon monoxide indicates that these elevated levels are found in association with continental outflow, demonstrating the critical role of the rapid transport of carbon monoxide and other ozone precursors from the continental boundary layer. In comparison with available ozonesonde data, it is found that the model-calculated ozone concentrations are generally in good agreement with the measurements, and the stratospheric contribution to surface ozone mixing ratios is quite limited.

Quantifying Uncontrolled Air Emissions from Two Florida Landfills

EPA Science Inventory

Landfill gas emissions, if left uncontrolled, contribute to air toxics, climate change, trospospheric ozone, and urban smog. Measuring emissions from landfills presents unique challenges due to the large and variable source area, spatial and temporal variability of emissions, and...

Long-term total ozone observations at Arosa (Switzerland) with Dobson and Brewer instruments (1988-2007)

NASA Astrophysics Data System (ADS)

Scarnato, B.; Staehelin, J.; Stübi, R.; Schill, H.

2010-07-01

Dobson and Brewer spectrophotometers are the standard instruments for ground-based total ozone monitoring under the World Meteorological Organization's Global Atmosphere Watch program. Both types of instruments have been simultaneously used at Arosa station (Switzerland) since 1988; presently two Dobson and three Brewer instruments (one of which is type Mark III) are in operation. The large data set of quasi-simultaneous measurements (defined here as observations performed less than 10 min apart) allows for the determination of both inter- and intrainstrumental precision. The results for one standard deviation of total ozone are ±0.5% for Dobson standard wavelength pair observations and ±0.15% for Brewer total ozone measurements. To transform Dobson data into Brewer total ozone observations, empirical transfer functions are used to describe the observed difference in seasonal variations of total ozone data derived from the two types of instruments (amounting to a seasonal amplitude of approximately 2% with maximum deviation in winter). The statistical model (applied to quasi-simultaneous measurements) includes the ozone effective temperature and the air mass multiplied by total ozone (ozone slant path) as explanatory variables; it removes the seasonal cycle in the difference and it allows the significance of the proxies introduced and systematic errors in the data to be determined. However, even when these transfer functions are applied, a 3% drift over about a 10 year period (1988-1997) between Arosa's Dobson and Brewer derived total ozone data series remains unexplained, adding to the model an aerosol proxy for which only part of the drift can be removed (related to the period 1992-1996).

Stratospheric ozone variations in the equatorial region as seen in Stratiospheric Aerosol and Gas Experiment data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiotani, M.; Hasebe, F.

1994-07-01

An analysis is made of equatorial ozone variations for 5 years, 1984-1989, using the ozone profile data derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument. Attention is focused on the annual cycle and also on interannual variability, particularly the quasi-biennial oscillation (QBO) and El Nino-Southern Oscillation (ENSO) variations in the lower stratosphere, where the largest contribution to total column ozone takes place. The annual variation in zonal mean total ozone around the equator is composed of symmetric and asymmetric modes with respect to the equator, with maximum contributions being around 19 km for the symmetric modemore » and around 25 km for the asymmetric mode. The persistent zonal wavenumber 1 structure observed by the total ozone mapping spectrometer over the equator is almost missing in the SAGE-derived column amounts integrated in the stratosphere, suggesting a significant contribution from tropospheric ozone. Interannual variations in the equatorial ozone are dominated by the QBO above 20 km and the ENSO-related variation below 20 km. The ozone QBO is characterized by zonally uniform phase changes in association with the zonal wind QBO in the equatorial lower stratosphere. The ENSO-related ozone variation consists of both the east-west vacillation and the zonally uniform phase variation. During the El Nino event, the east-west contrast with positive (negative) deviations in the eastern (western) hemisphere is conspicuous, while the decreasing tendency of the zonal mean values is maximum at the same time.« less

Stratospheric ozone variations in the equatorial region as seen in Stratospheric and Gas Experiment data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masato Shiotani; Fumio Hasebe

1994-07-20

An analysis is made of equatorial ozone variations for 5 years, 1984-1989, using the ozone profile data derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument. Attention is focused on the annual cycle and also on interannual variability, particularly the quasi-biennial oscillation (QBO) and El Nino-Southern Oscillation (ENSO) variations in the lower stratosphere, where the largest contribution to total column ozone takes place. The annual variation in zonal mean total ozone around the equator is composed of symmetric and asymmetric modes with respect to the equator, with maximum contributions being around 19 km for the symmetric modemore » and around 25 km for the asymmetric mode. The persistent zonal wavenumber 1 structure observed by the total ozone mapping spectrometer over the equator is almost missing in the SAGE-derived column amounts integrated in the stratosphere, suggesting a significant contribution from tropospheric ozone. Interannual variations in the equatorial ozone are dominated by the QBO above 20 km and the ENSO-related variation below 20 km. The ozone QBO is characterized by zonally uniform phase changes in association with the zonal wind QBO in the equatorial lower stratosphere. The ENSO-related ozone variation consists of both the east-west vacillation and the zonally uniform phase variation. During the El Nino event, the east-west contrast with positive (negative) deviations in the eastern (western) hemisphere is conspicuous, while the decreasing tendency of the zonal mean values is maximum at the same time. 28 refs., 13 figs.« less

Tropospheric Ozone Lidar Network (TOLNet) - Long-term Tropospheric Ozone and Aerosol Profiling for Satellite Continuity and Process Studies

NASA Astrophysics Data System (ADS)

Newchurch, M.; Al-Saadi, J. A.; Alvarez, R. J.; Burris, J.; Cantrell, W.; Chen, G.; De Young, R.; Hardesty, R.; Hoff, R. M.; Kaye, J. A.; kuang, S.; Langford, A. O.; LeBlanc, T.; McDermid, I. S.; McGee, T. J.; Pierce, R.; Senff, C. J.; Sullivan, J. T.; Szykman, J.; Tonnesen, G.; Wang, L.

2012-12-01

An interagency research initiative for ground-based ozone and aerosol lidar profiling recently funded by NASA has important applications to air-quality studies in addition to the goal of serving the GEO-CAPE and other air-quality missions. Ozone is a key trace-gas species, a greenhouse gas, and an important pollutant in the troposphere. High spatial and temporal variability of ozone affected by various physical and photochemical processes motivates the high spatio-temporal lidar profiling of tropospheric ozone for improving the simulation and forecasting capability of the photochemical/air-quality models, especially in the boundary layer where the resolution and precision of satellite retrievals are fundamentally limited. It is well known that there are large discrepancies between the surface and upper-air ozone due to titration, surface deposition, diurnal processes, free-tropospheric transport, and other processes. Near-ground ozone profiling has been technically challenging for lidars due to some engineering difficulties, such as near-range saturation, field-of-view overlap, and signal processing issues. This initiative provides an opportunity for us to solve those engineering issues and redesign the lidars aimed at long-term, routine ozone/aerosol observations from the near surface to the top of the troposphere at multiple stations (i.e., NASA/GSFC, NASA/LaRC, NASA/JPL, NOAA/ESRL, UAHuntsville) for addressing the needs of NASA, NOAA, EPA and State/local AQ agencies. We will present the details of the science investigations, current status of the instrumentation development, data access/protocol, and the future goals of this lidar network. Ozone lidar/RAQMS comparison of laminar structures.

A Lagrangian analysis of the impact of transport and transformation on the ozone stratification observed in the free troposphere during the ESCOMPTE campaign

NASA Astrophysics Data System (ADS)

Colette, A.; Ancellet, G.; Menut, L.; Arnold, S. R.

2006-03-01

The ozone variability observed by tropospheric ozone lidars during the ESCOMPTE campaign is analyzed by means of a hybrid-Lagrangian modeling study. Transport processes responsible for the formation of ozone-rich layers are identified using a semi-Lagrangian analysis of mesoscale simulations to identify the planetary boundary layer (PBL) footprint in the free troposphere. High ozone concentrations are related to polluted air masses exported from the Iberian PBL. The chemical composition of air masses coming from the PBL and transported in the free troposphere is evaluated using a Lagrangian chemistry model. The initial concentrations are provided by a model of chemistry and transport. Different scenarios are tested for the initial conditions and for the impact of mixing with background air in order to perform a quantitative comparison with the lidar observations. For this meteorological situation, the characteristic mixing time is of the order of 2 to 5 days depending on the initial conditions. Ozone is produced in the free troposphere within most air masses exported from the Iberian PBL at an average rate of 0.2 ppbv h-1, with a maximum ozone production of 0.4 ppbv h-1. Transport processes from the PBL are responsible for an increase of 13.3 ppbv of ozone concentrations in the free troposphere compared to background levels; about 45% of this increase is attributed to in situ production during the transport rather than direct export of ozone.

A Lagrangian analysis of the impact of transport and transformation on the ozone stratification observed in the free troposphere during the ESCOMPTE campaign

NASA Astrophysics Data System (ADS)

Colette, A.; Ancellet, G.; Menut, L.; Arnold, S. R.

2006-08-01

The ozone variability observed by tropospheric ozone lidars during the ESCOMPTE campaign is analyzed by means of a hybrid-Lagrangian modeling study. Transport processes responsible for the formation of ozone-rich layers are identified using a semi-Lagrangian analysis of mesoscale simulations to identify the planetary boundary layer (PBL) footprint in the free troposphere. High ozone concentrations are related to polluted air masses exported from the Iberian PBL. The chemical composition of air masses coming from the PBL and transported in the free troposphere is evaluated using a Lagrangian chemistry model. The initial concentrations are provided by a model of chemistry and transport. Different scenarios are tested for the initial conditions and for the impact of mixing with background air in order to perform a quantitative comparison with the lidar observations. For this meteorological situation, the characteristic mixing time is of the order of 2 to 6 days depending on the initial conditions. Ozone is produced in the free troposphere within most air masses exported from the Iberian PBL at an average rate of 0.2 ppbv h-1, with a maximum ozone production of 0.4 ppbv h-1. Transport processes from the PBL are responsible for an increase of 13.3 ppbv of ozone concentrations in the free troposphere compared to background levels; about 45% of this increase is attributed to in situ production during the transport rather than direct export of ozone.

Inactivation of Template-Directed Misfolding of Infectious Prion Protein by Ozone

PubMed Central

Ding, Ning; Price, Luke M.; Braithwaite, Shannon L.; Balachandran, Aru; Belosevic, Miodrag

2012-01-01

Misfolded prions (PrPSc) are well known for their resistance to conventional decontamination processes. The potential risk of contamination of the water environment, as a result of disposal of specified risk materials (SRM), has raised public concerns. Ozone is commonly utilized in the water industry for inactivation of microbial contaminants and was tested in this study for its ability to inactivate prions (263K hamster scrapie = PrPSc). Treatment variables included initial ozone dose (7.6 to 25.7 mg/liter), contact time (5 s and 5 min), temperature (4°C and 20°C), and pH (pH 4.4, 6.0, and 8.0). Exposure of dilute suspensions of the infected 263K hamster brain homogenates (IBH) (0.01%) to ozone resulted in the in vitro destruction of the templating properties of PrPSc, as measured by the protein misfolding cyclic amplification (PMCA) assay. The highest levels of prion inactivation (≥4 log10) were observed with ozone doses of 13.0 mg/liter, at pH 4.4 and 20°C, resulting in a CT (the product of residual ozone concentration and contact time) value as low as 0.59 mg · liter−1 min. A comparison of ozone CT requirements among various pathogens suggests that prions are more susceptible to ozone degradation than some model bacteria and protozoa and that ozone treatment may be an effective solution for inactivating prions in water and wastewater. PMID:22138993

The 1998-2000 SHADOZ (Southern Hemisphere ADditional OZonesondes) Tropical Ozone Climatology: Ozonesonde Precision, Accuracy and Station-to-Station Variability

NASA Technical Reports Server (NTRS)

Witte, J. C.; Thompson, Anne M.; McPeters, R. D.; Oltmans, S. J.; Schmidlin, F. J.; Bhartia, P. K. (Technical Monitor)

2001-01-01

As part of the SAFARI-2000 campaign, additional launches of ozonesondes were made at Irene, South Africa and at Lusaka, Zambia. These represent campaign augmentations to the SHADOZ database described in this paper. This network of 10 southern hemisphere tropical and subtropical stations, designated the Southern Hemisphere ADditional OZonesondes (SHADOZ) project and established from operational sites, provided over 1000 profiles from ozonesondes and radiosondes during the period 1998-2000. (Since that time, two more stations, one in southern Africa, have joined SHADOZ). Archived data are available at: http://code9l6.gsfc.nasa.gov/Data-services/shadoz>. Uncertainties and accuracies within the SHADOZ ozone data set are evaluated by analyzing: (1) imprecisions in stratospheric ozone profiles and in methods of extrapolating ozone above balloon burst; (2) comparisons of column-integrated total ozone from sondes with total ozone from the Earth-Probe/TOMS (Total Ozone Mapping Spectrometer) satellite and ground-based instruments; (3) possible biases from station-to-station due to variations in ozonesonde characteristics. The key results are: (1) Ozonesonde precision is 5%; (2) Integrated total ozone column amounts from the sondes are in good agreement (2-10%) with independent measurements from ground-based instruments at five SHADOZ sites and with overpass measurements from the TOMS satellite (version 7 data). (3) Systematic variations in TOMS-sonde offsets and in groundbased-sonde offsets from station to station reflect biases in sonde technique as well as in satellite retrieval. Discrepancies are present in both stratospheric and tropospheric ozone. (4) There is evidence for a zonal wave-one pattern in total and tropospheric ozone, but not in stratospheric ozone.

A statistical model to predict total column ozone in Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Tan, K. C.; Lim, H. S.; Mat Jafri, M. Z.

2016-03-01

This study aims to predict monthly columnar ozone in Peninsular Malaysia based on concentrations of several atmospheric gases. Data pertaining to five atmospheric gases (CO2, O3, CH4, NO2, and H2O vapor) were retrieved by satellite scanning imaging absorption spectrometry for atmospheric chartography from 2003 to 2008 and used to develop a model to predict columnar ozone in Peninsular Malaysia. Analyses of the northeast monsoon (NEM) and the southwest monsoon (SWM) seasons were conducted separately. Based on the Pearson correlation matrices, columnar ozone was negatively correlated with H2O vapor but positively correlated with CO2 and NO2 during both the NEM and SWM seasons from 2003 to 2008. This result was expected because NO2 is a precursor of ozone. Therefore, an increase in columnar ozone concentration is associated with an increase in NO2 but a decrease in H2O vapor. In the NEM season, columnar ozone was negatively correlated with H2O (-0.847), NO2 (0.754), and CO2 (0.477); columnar ozone was also negatively but weakly correlated with CH4 (-0.035). In the SWM season, columnar ozone was highly positively correlated with NO2 (0.855), CO2 (0.572), and CH4 (0.321) and also highly negatively correlated with H2O (-0.832). Both multiple regression and principal component analyses were used to predict the columnar ozone value in Peninsular Malaysia. We obtained the best-fitting regression equations for the columnar ozone data using four independent variables. Our results show approximately the same R value (≈ 0.83) for both the NEM and SWM seasons.

Ozone and UV-B variations at Ispra from 1993 to 1997

NASA Astrophysics Data System (ADS)

Cappellani, F.; Kochler, C.

An analysis of the variability of the total ozone column at Ispra (Italy) has been performed to ascertain if, even in a short-time interval of 5 years (1993-1997), a decline of the monthly mean ozone values could be demonstrated. A linear fit of the data displays a decrease of 0.21% per year with a mean value equal to 319±2 D.U. and an amplitude of the annual cycle of about 10% of the mean. A linear regression of the surface monthly mean ozone values has also been performed showing a decreasing trend (-1% per year) that could contribute, even if for a very small amount, to the decline of the total ozone values. Ispra monthly mean total ozone data have been compared with those of three stations located within 2° latitude and 3° longitude from Ispra (Haute Provence, Hohenpeissenberg and Arosa). A linear fit of the data shows some discrepancies in the ozone changes, which can be attributed to the limited length of the observational period. An analysis has been performed to verify if the variation of ozone at Ispra is in agreement with that of the solar UV measured at a wavelength (305 nm) where the ozone absorption is still remarkable. The results, taken at a fixed solar zenith angle of 68°, show a clear anticorrelation between the monthly mean values of UV and the corresponding values of the total ozone column; the linear fit of the UV data displays an increase of 2.0% per year, much higher than expected from the ozone decrease, and a mean value of 1.4±0.1 mW m -2 nm -1.