Data composites of airborne observations of tropospheric ozone and its precursors

Emmons, L. K.; Hauglustaine, Didier; Müller, Jean-François; Carroll, Mary Anne; Brasseur, Guy; Brunner, Dominik; Staehelin, J.; Thouret, V.; Marenco, A.

doi:10.1029/2000jd900232

Cited by 209 publications

(299 citation statements)

References 135 publications

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“…Nevertheless, the modelled NO x concentrations are generally in reasonable agreement with observations especially in the mid troposphere (see Fig. 4 seen in the middle to upper tropospheric over the South Atlantic during September-November are from biomass burning emissions that have been transported from the continents (PEM-Tropics-A and Tracer-A) (see Emmons et al, 2000, and references therein); this is not reproduced by the model. Note that the modelled data are the average over 5 years; hence they do not capture interannual variability of emissions (which are the same for every year of the model run) and meterological conditions.…”

Section: Nitrogen Speciesmentioning

confidence: 62%

“…Here we emphasize speciated comparisons; we compare some measured and modelled NO x and PAN vertical profiles. The observation data are from short-term aircraft campaigns compiled by Emmons et al (2000) and should not necessarily compare in detail with model results from a climate simulation. Nevertheless, the modelled NO x concentrations are generally in reasonable agreement with observations especially in the mid troposphere (see Fig.…”

Section: Nitrogen Speciesmentioning

confidence: 99%

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Impact of climate change on tropospheric ozone and its global budgets

2008

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Abstract.We present the chemistry-climate model UM CAM in which a relatively detailed tropospheric chemical module has been incorporated into the UK Met Office's Unified Model version 4.5. We obtain good agreements between the modelled ozone/nitrogen species and a range of observations including surface ozone measurements, ozone sonde data, and some aircraft campaigns.Four 2100 calculations assess model responses to projected changes of anthropogenic emissions (SRES A2), climate change (due to doubling CO 2 ), and idealised climate change-associated changes in biogenic emissions (i.e. 50% increase of isoprene emission and doubling emissions of soil-NO x ). The global tropospheric ozone burden increases significantly for all the 2100 A2 simulations, with the largest response caused by the increase of anthropogenic emissions. Climate change has diverse impacts on O 3 and its budgets through changes in circulation and meteorological variables. Increased water vapour causes a substantial ozone reduction especially in the tropical lower troposphere (>10 ppbv reduction over the tropical ocean). On the other hand, an enhanced stratosphere-troposphere exchange of ozone, which increases by 80% due to doubling CO 2 , contributes to ozone increases in the extratropical free troposphere which subsequently propagate to the surface. Projected higher temperatures favour ozone chemical production and PAN decomposition which lead to high surface ozone levels in certain regions. Enhanced convection transports ozone precursors more rapidly out of the boundary layer resulting in an increase of ozone production in the free troposphere. Lightning-produced NO x increases by about 22% in the doubled CO 2 climate and contributes to ozone production.The response to the increase of isoprene emissions shows that the change of ozone is largely determined by background NO x levels: high NO x environment increases ozone producCorrespondence to: G. Zeng (guang.zeng@atm.ch.cam.ac.uk) tion; isoprene emitting regions with low NO x levels see local ozone decreases, and increase of ozone levels in the remote region due to the influence of PAN chemistry. The calculated ozone changes in response to a 50% increase of isoprene emissions are in the range of between −8 ppbv to 6 ppbv. Doubling soil-NO x emissions will increase tropospheric ozone considerably, with up to 5 ppbv in source regions.

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Section: Nitrogen Speciesmentioning

confidence: 62%

Section: Nitrogen Speciesmentioning

confidence: 99%

Impact of climate change on tropospheric ozone and its global budgets

2008

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“…Comparisons with NOx measurements in the free troposphere should identify which models match the observations and if these predict similar aviation impacts. However, current NOx climatologies (40) are assembled from campaigns of opportunity and do not have the necessary statistics or coverage to adequately test the models. An observational NOx climatology that includes HOx (OH þ HO 2 ) sources and samples a wide range of latitudes and photochemical regimes in both hemispheres at seasonal intervals would aid process studies in global atmospheric chemistry and their application to changing emissions and climate.…”

Section: Discussionmentioning

confidence: 99%

Uncertainties in climate assessment for the case of aviation NO

Holmes

Tang²,

Prather³

2011

Proc. Natl. Acad. Sci. U.S.A.

122

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Nitrogen oxides emitted from aircraft engines alter the chemistry of the atmosphere, perturbing the greenhouse gases methane (CH 4 ) and ozone (O 3 ). We quantify uncertainties in radiative forcing (RF) due to short-lived increases in O 3 , long-lived decreases in CH 4 and O 3 , and their net effect, using the ensemble of published models and a factor decomposition of each forcing. The decomposition captures major features of the ensemble, and also shows which processes drive the total uncertainty in several climate metrics. Aviation-specific factors drive most of the uncertainty for the short-lived O 3 and long-lived CH 4 RFs, but a nonaviation factor dominates for long-lived O 3 . The model ensemble shows strong anticorrelation between the short-lived and long-lived RF perturbations (R 2 ¼ 0.87). Uncertainty in the net RF is highly sensitive to this correlation. We reproduce the correlation and ensemble spread in one model, showing that processes controlling the background tropospheric abundance of nitrogen oxides are likely responsible for the modeling uncertainty in climate impacts from aviation.aviation emissions | error correlation | model sensitivity Q uantifying uncertainties in climate processes is a major priority for climate research, as exemplified by the widespread use of probability distributions and uncertainties in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (1). To understand and attribute changes in the greenhouse gases and aerosols that force climate change, we rely on chemistry-transport models (CTMs), which require further characterization of their errors (e.g., 2-5). Aviation emissions are estimated to contribute 5% of anthropogenic climate forcing, with a nearly threefold uncertainty (6). This forcing occurs mainly through aviation-induced cloudiness and emissions of CO 2 and nitrogen oxides. Climate impacts of other aviation emissions-CO, SO 2 , soot, hydrocarbons, and water vapor-are highly uncertain, but estimated to be much smaller (6). In this paper we quantify one type of climate forcing and its uncertainty, the impact of aviation emissions on the greenhouse gases ozone (O 3 ) and methane (CH 4 ).Aircraft engines emit NO and NO 2 (NOx), which are indirect greenhouse gases through their chemical reactions impacting O 3 production and the CH 4 lifetime. As an O 3 precursor, NOx emissions increase the tropospheric column of O 3 and its radiative forcing. Aviation NOx emissions have a stronger impact on O 3 than surface emissions on a per molecule basis because they occur at high altitudes (7). Previous model-based estimates of the amount of O 3 generated by aviation NOx emissions vary by up to 100% and these differences have been attributed to a range of causes: e.g., the ratios of NO∶NO 2 and OH∶HO 2 , background NOx levels (8), location and time of emissions (9-11), the amount of sunlight (12), and atmospheric mixing (13,14).Early work on climate forcing by aviation assumed that the impacts would be short-lived and limited to the northern latitudes ...

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“…Long-term measurements of CO have helped to characterise the spatial and temporal variability and estimate the global and regional budget of CO (Emmons et al, 2000;Duncan et al, 2007). Such measurements are however sparse over South Asia, where long-term vertical profile measurements of CO are crucial to study the effect of longrange transport on the seasonality and interannual variability of CO in the free troposphere (Sheel et al, 2014).…”

Section: Introductionmentioning

confidence: 99%