Tropospheric ozone

About: Tropospheric ozone is a research topic. Over the lifetime, 3507 publications have been published within this topic receiving 142352 citations.

Chemistry of the Upper and Lower Atmosphere: Theory, Experiments, and Applications

Abstract: Overview of the Chemistry of Polluted and Remote Atmospheres. The Atmospheric System. Spectroscopy and Photochemistry: Fundamentals. Photochemistry of Important Atmospheric Species. Kinetics and Atmospheric Chemistry. Rates and Mechanisms of Gas-Phase Reactions in Irradiated Organic-NOx-Air Mixtures. Chemistry of Inorganic Nitrogen Compounds. Acid Deposition: Formation and Fates of Inorganic and Organic Acids in the Troposphere. Particles in the Troposphere. Airborne Polycyclic Aromatic Hydrocarbons and Their Derivatives: Atmospheric Chemistry and Toxicological Implications. Analytical Methods and Typical Atmospheric Concentrations for Gases and Particles. Homogeneous and Heterogeneous Chemistry in the Stratosphere. Scientific Basis for Control of Halogenated Organics. Global Tropospheric Chemistry and Climate Change. Indoor Air Pollution: Sources, Levels, Chemistry, and Fates. Applications of Atmospheric Chemistry: Air Pollution Control Strategies and Risk Assessments for Tropospheric Ozone and Associated Photochemical Oxidants, Acids, Particles, and Hazardous Air Pollutants. Appendix I: Enthalpies of Formation of Some Gaseous Molecules, Atoms, and Free Radicals at 298 K. Appendix II: Bond Dissociation Energies. Appendix III: Running the OZIPR Model. Appendix IV: Some Relevant Web Sites. Appendix V: Pressures and Temperatures for Standard Atmosphere. Appendix VI: Answers to Selected Problems. Subject Index.

Radiative forcing and climate response

Abstract: We examine the sensitivity of a climate model to a wide range of radiative forcings, including changes of solar irradiance, atmospheric CO2, O3, CFCs, clouds, aerosols, surface albedo, and a “ghost” forcing introduced at arbitrary heights, latitudes, longitudes, seasons, and times of day. We show that, in general, the climate response, specifically the global mean temperature change, is sensitive to the altitude, latitude, and nature of the forcing; that is, the response to a given forcing can vary by 50% or more depending upon characteristics of the forcing other than its magnitude measured in watts per square meter. The consistency of the response among different forcings is higher, within 20% or better, for most of the globally distributed forcings suspected of influencing global mean temperature in the past century, but exceptions occur for certain changes of ozone or absorbing aerosols, for which the climate response is less well behaved. In all cases the physical basis for the variations of the response can be understood. The principal mechanisms involve alterations of lapse rate and decrease (increase) of large-scale cloud cover in layers that are preferentially heated (cooled). Although the magnitude of these effects must be model-dependent, the existence and sense of the mechanisms appear to be reasonable. Overall, we reaffirm the value of the radiative forcing concept for predicting climate response and for comparative studies of different forcings; indeed, the present results can help improve the accuracy of such analyses and define error estimates. Our results also emphasize the need for measurements having the specificity and precision needed to define poorly known forcings such as absorbing aerosols and ozone change. Available data on aerosol single scatter albedo imply that anthropogenic aerosols cause less cooling than has commonly been assumed. However, negative forcing due to the net ozone change since 1979 appears to have counterbalanced 30–50% of the positive forcing due to the increase of well-mixed greenhouse gases in the same period. As the net ozone change includes halogen-driven ozone depletion with negative radiative forcing and a tropospheric ozone increase with positive radiative forcing, it is possible that the halogen-driven ozone depletion has counterbalanced more than half of the radiative forcing due to well-mixed greenhouse gases since 1979.

Increase in tropospheric nitrogen dioxide over China observed from space

Abstract: The rapid expansion of the Chinese economy is making its mark on the environment. Atmospheric pollution due to the release of nitrogen oxides from fossil fuel and biomass burning is expected to decrease in most industrialized countries but in some parts of the world rapid economic development could have the opposite effect. Satellite observations over the period 1996–2004 now provide confirmation of these predictions. Across parts of Europe and North America there have been dramatic reductions in nitrogen oxide concentrations in the lower atmosphere (the troposphere). But there was a significant increase of about 50% — with an accelerating trend in annual growth rate — over the industrial areas of China; this is much larger than predictions made based on emission inventories. Emissions from fossil fuel combustion and biomass burning reduce local air quality and affect global tropospheric chemistry. Nitrogen oxides are emitted by all combustion processes and play a key part in the photochemically induced catalytic production of ozone, which results in summer smog and has increased levels of tropospheric ozone globally1. Release of nitrogen oxide also results in nitric acid deposition, and—at least locally—increases radiative forcing effects due to the absorption of downward propagating visible light2. Nitrogen oxide concentrations in many industrialized countries are expected to decrease3, but rapid economic development has the potential to increase significantly the emissions of nitrogen oxides4,5,6,7 in parts of Asia. Here we present the tropospheric column amounts of nitrogen dioxide retrieved from two satellite instruments GOME8,9 and SCIAMACHY10 over the years 1996–2004. We find substantial reductions in nitrogen dioxide concentrations over some areas of Europe and the USA, but a highly significant increase of about 50 per cent—with an accelerating trend in annual growth rate—over the industrial areas of China, more than recent bottom-up inventories suggest6.

Multimodel ensemble simulations of present-day and near-future tropospheric ozone

Abstract: Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state-of-the-art atmospheric chemistry models have been intercompared and synthesized as part of a wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing optimistic, likely, and pessimistic options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5% decrease, through a 6% increase, to a 15% increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25%. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of -50, 180, and 300 mW m-2, compared to a CO 2 forcing over the same time period of 800-1100 mW m-2. These values indicate the importance of air pollution emissions in short- to medium-term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere-troposphere exchange. This level of climate change also reduces the methane lifetime by around 4%. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000 and 550 Tg(O 3 ) yr-1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O 3 )) is 10% larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10% shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NO x production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere-troposphere exchange; biomass burning; and water vapor concentrations. Copyright 2006 by the American Geophysical Union.

Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security

Abstract: Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide–reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.