91 results on '"Pyle, J.A."'
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2. Use of Satellite Data to Constrain Ozone Budgets in Global Tropospheric Chemistry Models
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Savage, Nicholas Henry, Richter, Andreas, Wittrock, F., Ladstaetter-Weissenmayer, A., Edwards, G., Remedios, John J., Law, K., O’Connor, F., Pyle, J.A., Burrows, John P., Borrell, Peter, editor, Borrell, Patricia M., editor, Burrows, John P., editor, and Platt, Ulrich, editor
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- 2004
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3. Rising methane: is there a methane emergency? [Preface]
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Nisbet, E.G., Jones, A.E., Pyle, J.A., Skiba, U., Nisbet, E.G., Jones, A.E., Pyle, J.A., and Skiba, U.
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These two volumes of the Royal Society's Philosophical Transactions record the ‘state of methane’ in 2021. The atmospheric methane burden rose rapidly in 2020: more rapidly than at any previous time in the observational record. The causes of this rise are complex and not well understood. It is likely much of the growth is driven by increased emissions from biological sources, such as natural wetlands, agriculture and landfills, especially in the Tropics and sub-Tropics. Other processes such as declining methane sinks may also be contributing. The methane budget is not closed. In the overall estimates by Saunois et al. (2020), there are wide uncertainty margins in each sub-category and huge discrepancies between Top-Down and Bottom-Up assessments. Moreover, in seeking to track methane, we are chasing a very fast-changing target—the global methane budget in 2021 is very different from the budget in 2010.
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- 2022
4. STRATOSPHERIC CHEMISTRY TOPICS | Overview
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Pyle, J.A., primary
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- 2015
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5. A strategy for process-oriented validation of coupled chemistry--climate models
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Eyring, V., Harris, N.R.P., Rex, M., Shepherd, T.G., Fahey, D.W., Amanatidis, G.T., Austin, J., Chipperfield, M.P., Dameris, M., De F., Forster, P.M., Gettelman, A., Graf, H.F., Nagashima, T., Newman, P.A., Pawson, S., Prather, M.J., Pyle, J.A., Salawitch, R.J., Santer, B.D., and Waugh, D.W.
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Climatic changes -- Research ,Stratosphere -- Research ,Meteorology -- Research ,Business ,Earth sciences - Abstract
Accurate and reliable predictions and an understanding of future changes in the stratosphere are major aspects of the subject of climate change. Simulating the interaction between chemistry and climate is of particular importance, because continued increases in greenhouse gases and a slow decrease in halogen loading are expected. These both influence the abundance of stratospheric ozone. In recent years a number of coupled chemistry-climate models (CCMs) with different levels of complexity have been developed. They produce a wide range of results concerning the timing and extent of ozone-layer recovery. Interest in reducing this range has created a need to address how the main dynamical, chemical, and physical processes that determine the long-term behavior of ozone are represented in the models and to validate these model processes through comparisons with observations and other models. A set of core validation processes structured around four major topics (transport, dynamics, radiation, and stratospheric chemistry and microphysics) has been developed. Each process is associated with one or more model diagnostics and with relevant datasets that can be used for validation. This approach provides a coherent framework for validating CCMs and can be used as a basis for future assessments. Similar efforts may benefit other modeling communities with a focus on earth science research as their models increase in complexity.
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- 2005
6. OZONE | Ozone Depletion
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Pyle, J.A., primary
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- 2003
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7. STRATOSPHERIC CHEMISTRY AND COMPOSITION | Overview
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Pyle, J.A., primary
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- 2003
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8. Heterogeneous reaction of ClONO2 with TiO2 and SiO2 aerosol particles: implications for stratospheric particle injection for climate engineering
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Tang, M., Keeble, J., Telford, P.J., Pope, F.D., Braesicke, P., Griffiths, P.T., Abraham, N.L., McGregor, J., Watson, I.M., Cox, R.A., Pyle, J.A., Kalberer, M., Keeble, James [0000-0003-2714-1084], Griffiths, Paul [0000-0002-1089-340X], Pyle, John [0000-0003-3629-9916], Kalberer, Markus [0000-0001-8885-6556], and Apollo - University of Cambridge Repository
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13 Climate Action ,3701 Atmospheric Sciences ,37 Earth Sciences - Abstract
Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Particles injected into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth's surface and hence the impacts of global warming. Minerals such as TiO$_{2}$ or SiO$_{2}$ are among the potentially suitable aerosol materials for stratospheric particle injection due to their greater light-scattering ability than stratospheric sulfuric acid particles. However, the heterogeneous reactivity of mineral particles towards trace gases important for stratospheric chemistry largely remains unknown, precluding reliable assessment of their impacts on stratospheric ozone, which is of key environmental significance. In this work we have investigated for the first time the heterogeneous hydrolysis of ClONO$_{2}$ on TiO$_{2}$ and SiO$_{2}$ aerosol particles at room temperature and at different relative humidities (RHs), using an aerosol flow tube. The uptake coefficient, γ(ClONO$_{2}$), on TiO$_{2}$ was ∼ 1.2 × 10$^{-3}$ at 7 % RH and remained unchanged at 33 % RH, and increased for SiO$_{2}$ from ∼ 2 × 10$^{-4}$ at 7 % RH to ∼ 5 × 10$^{-4}$ at 35 % RH, reaching a value of ∼ 6 × 10$^{-4}$ at 59 % RH. We have also examined the impacts of a hypothetical TiO$_{2}$ injection on stratospheric chemistry using the UKCA (United Kingdom Chemistry and Aerosol) chemistry–climate model, in which heterogeneous hydrolysis of N$_{2}$O$_{5}$ and ClONO$_{2}$ on TiO$_{2}$ particles is considered. A TiO$_{2}$ injection scenario with a solar-radiation scattering effect very similar to the eruption of Mt Pinatubo was constructed. It is found that, compared to the eruption of Mt Pinatubo, TiO$_{2}$ injection causes less ClO$_{x}$ activation and less ozone destruction in the lowermost stratosphere, while reduced depletion of N$_{2}$O$_{5}$ and NO$_{x}$ in the middle stratosphere results in decreased ozone levels. Overall, no significant difference in the vertically integrated ozone abundances is found between TiO$_{2}$ injection and the eruption of Mt Pinatubo. Future work required to further assess the impacts of TiO$_{2}$ injection on stratospheric chemistry is also discussed.
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- 2016
9. Evaluation of a Lagrangian box model using field measurements from EASE (Eastern Atlantic Summer Experiment) 1996
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Evans, M.J, Shallcross, D.E, Law, K.S, Wild, J.O.F, Simmonds, P.G, Spain, T.G, Berrisford, P, Methven, J, Lewis, A.C, McQuaid, J.B, Pilling, M.J, Bandy, B.J, Penkett, S.A, and Pyle, J.A
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- 2000
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10. Effect of ozone depletion on atmospheric CH4 and CO concentrations
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Bekki, S., Law, K.S., and Pyle, J.A.
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Ozone layer depletion -- Analysis ,Carbon monoxide -- Environmental aspects ,Methane -- Environmental aspects ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
A two-dimensional atmospheric model and the Total Ozone Mapping Spectrometer facilitate the study of the correlation between stratospheric ozone decrease and the changes in atmospheric CH4 and CO concentrations. Nearly half the fall in CH4 and CO growth rates in 1992 can be attributed to low values in stratospheric ozone concentration. Ozone depletion contributes to decrease in the growth rates of CH4 and CO by exposing the troposphere to more ultraviolet radiation.
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- 1994
11. Stratospheric ozone depletion by ClONO2 photolysis
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Toumi, R., Jones, R.L., and Pyle, J.A.
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Northern Hemisphere -- Environmental aspects ,Arctic regions -- Environmental aspects ,Ozone layer depletion -- Arctic ,Catalysis -- Influence ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Simulations of ozone concentrations within the Arctic vortex and at a mid-latitude Northern Hemisphere site were undertaken by using an artifically constructed model to ascertain the significance of an ozone-depleting catalytic cycle. Ozone loss was reported from March to May at the Arctic vortex and the mid-latitude Northern Hemisphere site and was caused by the CIONO2 cycle. However, this cycle was not found to be limited to the timing and location of polar stratospheric clouds. Therefore, it may be concluded that this cycle is responsible for ozone depletion at warm middle latitudes.
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- 1993
12. Role of sulphur photochemistry in tropical ozone changes after the eruption of Mount Pinatubo
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Bekki, S., Toumi, R., and Pyle, J.A.
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Mount Pinatubo -- Environmental aspects ,Ozone layer depletion -- Models ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
The eruption of Mount Pinatubo resulted in perturbations in the tropical ozone layer characterized by ozone reductions up to 24-25 kilometers and increases above 28 kilometers. The eruption also resulted in injection of alarge amount of sulfur dioxide in the stratosphere. Sulfur dioxide may form ozone as well as reduce ozone production depending on the radiation absorbed. The role of sulfur dioxide in the disturbances in the ozone layer after the Mount Pinatubo eruption was investigated by simulation modeling. The model was in good agreement with most of the ozone measurements following the eruption.
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- 1993
13. Highly vibrationally excited oxygen as a potential source of ozone in the upper stratosphere and mesosphere
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Toumi, R., Kerridge, B.J., and Pyle, J.A.
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Stratosphere -- Research ,Ozone layer -- Research ,Mesosphere -- Research ,Atmospheric chemistry -- Models ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Published
- 1991
14. A multi-model intercomparison of halogenated very short-lived substances (TransCom-VSLS): Linking oceanic emissions and tropospheric transport for a reconciled estimate of the stratospheric source gas injection of bromine
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Hossaini, R., Patra, P.K., Leeson, A.A., Krysztofiak, G., Abraham, N.L., Andrews, S.J., Archibald, A.T., Aschmann, J., Atlas, Elliot L., Belikov, D.A., Bönisch, H., Carpenter, L.J., Dhomse, S., Dorf, M., Engel, Anja, Feng, W., Fuhlbrügge, S., Griffiths, P.T., Harris, Neil R. P., Hommel, R., Keber, T., Krüger, K., Lennartz, S.T., Maksyutov, S., Mantle, H., Mills, G.P., Miller, B., Montzka, S.A., Moore, F., Navarro, M. A., Oram, D.E., Pfeilsticker, K., Pyle, J.A., Quack, B., Robinson, A.D., Saikawa, E., Saiz-Lopez, A., Sala, S., Sinnhuber, B.M., Taguchi, S., Tegtmeier, S., Lidster, R.T., Wilson, C., Ziska, F., Hossaini, R., Patra, P.K., Leeson, A.A., Krysztofiak, G., Abraham, N.L., Andrews, S.J., Archibald, A.T., Aschmann, J., Atlas, Elliot L., Belikov, D.A., Bönisch, H., Carpenter, L.J., Dhomse, S., Dorf, M., Engel, Anja, Feng, W., Fuhlbrügge, S., Griffiths, P.T., Harris, Neil R. P., Hommel, R., Keber, T., Krüger, K., Lennartz, S.T., Maksyutov, S., Mantle, H., Mills, G.P., Miller, B., Montzka, S.A., Moore, F., Navarro, M. A., Oram, D.E., Pfeilsticker, K., Pyle, J.A., Quack, B., Robinson, A.D., Saikawa, E., Saiz-Lopez, A., Sala, S., Sinnhuber, B.M., Taguchi, S., Tegtmeier, S., Lidster, R.T., Wilson, C., and Ziska, F.
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The first concerted multi-model intercomparison of halogenated very short-lived substances (VSLS) has been performed, within the framework of the ongoing Atmospheric Tracer Transport Model Intercomparison Project (TransCom). Eleven global models or model variants participated (nine chemical transport models and two chemistry-climate models) by simulating the major natural bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2), over a 20-year period (1993-2012). Except for three model simulations, all others were driven offline by (or nudged to) reanalysed meteorology. The overarching goal of TransCom-VSLS was to provide a reconciled model estimate of the stratospheric source gas injection (SGI) of bromine from these gases, to constrain the current measurement-derived range, and to investigate inter-model differences due to emissions and transport processes. Models ran with standardised idealised chemistry, to isolate differences due to transport, and we investigated the sensitivity of results to a range of VSLS emission inventories. Models were tested in their ability to reproduce the observed seasonal and spatial distribution of VSLS at the surface, using measurements from NOAA's long-term global monitoring network, and in the tropical troposphere, using recent aircraft measurements - including high-altitude observations from the NASA Global Hawk platform. The models generally capture the observed seasonal cycle of surface CHBr3 and CH2Br2 well, with a strong model-measurement correlation (r≥0.7) at most sites. In a given model, the absolute model-measurement agreement at the surface is highly sensitive to the choice of emissions. Large inter-model differences are apparent when using the same emission inventory, highlighting the challenges faced in evaluating such inventories at the global scale. Across the ensemble, most consistency is found within the tropics where most of the models (8 out of 11) achieve best agreement to surface CHBr3 observations using th
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- 2016
15. Isoprene chemistry in pristine and polluted Amazon environments: Eulerian and Lagrangian model frameworks and the strong bearing they have on our understanding of surface ozone and predictions of rainforest exposure to this priority pollutant
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Levine, J.G., MacKenzie, A.R., Squire, O.J., Archibald, A.T., Griffiths, P.T., Abraham, N.L., Pyle, J.A., Oram, D.E., Forster, G., Brito, J.F., Lee, J.D., Hopkins, J.R., Lewis, A.C., Bauguitte, S.J.B., Demarco, C.F., Artaxo, P., Messina, P., Lathière, J., Hauglustaine, D.A., House, E., Hewitt, C.N., Nemitz, E., Levine, J.G., MacKenzie, A.R., Squire, O.J., Archibald, A.T., Griffiths, P.T., Abraham, N.L., Pyle, J.A., Oram, D.E., Forster, G., Brito, J.F., Lee, J.D., Hopkins, J.R., Lewis, A.C., Bauguitte, S.J.B., Demarco, C.F., Artaxo, P., Messina, P., Lathière, J., Hauglustaine, D.A., House, E., Hewitt, C.N., and Nemitz, E.
- Abstract
This study explores our ability to simulate the atmospheric chemistry stemming from isoprene emissions in pristine and polluted regions of the Amazon basin. We confront two atmospheric chemistry models – a global, Eulerian chemistry-climate model (UM-UKCA) and a trajectory-based Lagrangian model (CiTTyCAT) – with recent airborne measurements of atmospheric composition above the Amazon made during the SAMBBA campaign of 2012. The simulations with the two models prove relatively insensitive to the chemical mechanism employed; we explore one based on the Mainz Isoprene Mechanism, and an updated one that includes changes to the chemistry of first generation isoprene nitrates (ISON) and the regeneration of hydroxyl radicals via the formation of hydroperoxy-aldehydes (HPALDS) from hydroperoxy radicals (ISO2). In the Lagrangian model, the impact of increasing the spatial resolution of trace gas emissions employed from 3.75° × 2.5° to 0.1° × 0.1° varies from one flight to another, and from one chemical species to another. What consistently proves highly influential on our simulations, however, is the model framework itself – how the treatment of transport, and consequently mixing, differs between the two models. The lack of explicit mixing in the Lagrangian model yields variability in atmospheric composition more reminiscent of that exhibited by the measurements. In contrast, the combination of explicit (and implicit) mixing in the Eulerian model removes much of this variability but yields better agreement with the measurements overall. We therefore explore a simple treatment of mixing in the Lagrangian model that, drawing on output from the Eulerian model, offers a compromise between the two models. We use this Lagrangian/Eulerian combination, in addition to the separate Eulerian and Lagrangian models, to simulate ozone at a site in the boundary layer downwind of Manaus, Brazil. The Lagrangian/Eulerian combination predicts a value for an AOT40-like accumulated exposure met
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- 2015
16. Impacts of HOx regeneration and recycling in the oxidation of isoprene: Consequences for the composition of past, present and future atmospheres
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Archibald, A.T., Levine, James G., Abraham, N.L., Cooke, M.C., Edwards, P.M., Heard, D.E., Jenkin, M.E., Karunaharan, A., Pike, R.C., Monks, P.S., Shallcross, D.E., Telford, P.J., Whalley, L.K., and Pyle, J.A.
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Chemistry ,Meteorology and Climatology ,Atmospheric Sciences - Abstract
A global chemistry-climate model is used to assess the impact on atmospheric composition of the regeneration and recycling of HOx in the photo-oxidation of isoprene. The impact is explored subject to present-day, pre-industrial and future climate/emission scenarios. Our calculations show that, in all cases, the inclusion of uni-molecular isomerisations of the isoprene hydroxy-peroxy radicals leads to enhanced production of HOx radicals and ozone. The global burden of ozone increases by 25–36 Tg (8–18%), depending on the climate/emissions scenario, whilst the changes in OH lead to decreases in the methane lifetime of between 11% in the future and 35% in the pre-industrial. Critically the size of the change in methane lifetime depends on the VOC/NOx emission ratio. The results of the present-day calculations suggest a certain amount of parameter refinement is still needed to reconcile the updated chemistry with field observations (particularly for HO2+RO2). However, the updated chemistry could have far-reaching implications for: future-climate predictions; projections of future oxidising capacity; and our understanding of past changes in oxidising capacity.
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- 2011
17. Reconciling the changes in atmospheric-methane sources and sinks between the Last Glacial Maximum and the pre-industrial era
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Levine, J.G., Wolff, E.W., Jones, A.E., Sime, L.C., Valdes, P.J., Archibald, A.T., Carver, G.D., Warwick, N.J., and Pyle, J.A.
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Chemistry ,Atmospheric Sciences - Abstract
We know from the ice record that the concentration of atmospheric methane, [CH4], at the Last Glacial Maximum (LGM) was roughly half that in the pre-industrial era (PI), buthow much of the difference was source-driven, and how much was sink-driven, remains uncertain. Recent developments include: a higher estimate of the LGM-PI change in methane emissions from wetlands―the dominant, natural methane source; and the possible recycling of OH consumed in isoprene oxidation―the principal methane sink. Here, in view of these developments, we use an atmospheric chemistry-transport model to re-examine the main factors affecting OH during this period: changes in air temperature and emissions of non-methane volatile organic compounds from vegetation. We find that their net effect was negligible(with and without an OH recycling mechanism), implyingthe change in [CH4] was almost entirely source driven―a conclusion that, though subject to significant uncertainties,can be reconciled with recent methane source estimates.
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- 2011
18. NOx and O3 above a tropical rainforest: an analysis with a global and box model
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Pike, R.C., Lee, J.D., Young, P.J., Carver, G.D., Yang, X., Warwick, N., Mollerq, S., Misztal, P., Langford, B., Stewart, David John, Reeves, C.E., Hewitt, C.N., and Pyle, J.A.
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A cross-platform field campaign, OP3, was conducted in the state of Sabah in Malaysian Borneo between April and July of 2008. Among the suite of observations recorded, the campaign included measurements of NOx and O3 – crucial outputs of any model chemistry mechanism. We describe the measurements of these species made from both the ground site and aircraft. We then use the output from two resolutions of the chemistry transport model p-TOMCAT to illustrate the ability of a global model chemical mechanism to capture the chemistry at the rainforest site. The basic model performance is good for NOx and poor for ozone. A box model containing the same chemical mechanism is used to explore the results of the global model in more depth and make comparisons between the two. Without some parameterization of the nighttime boundary layer – free troposphere mixing (i.e. the use of a dilution parameter), the box model does not reproduce the observations, pointing to the importance of adequately representing physical processes for comparisons with surface measurements. We conclude with a discussion of box model budget calculations of chemical reaction fluxes, deposition and mixing, and compare these results to output from p-TOMCAT. These show the same chemical mechanism behaves similarly in both models, but that emissions and advection play particularly strong roles in influencing the comparison to surface measurements.
- Published
- 2010
19. Overview: oxidant and particle photochemical processes above a south-east Asian tropical rain forest (the OP3 project); introduction, rationale, location, characteristics and tools
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Hewitt, C.N., Lee, J.D., MacKenzie, A.R., Barkley, M.P., Carslaw, N., Carver, G.D., Chappell, N.A., Coe, H., Collier, C., Commane, R., Davies, F., Davison, B., DiCarlo, P., Di Marco, C.F., Dorsey, J.R., Edwards, P.M., Evans, M.J., Fowler, D., Furneaux, K.L., Gallagher, M., Guenther, A., Heard, D.E., Helfter, C., Hopkins, J., Ingham, T., Irwin, M., Jones, C., Karunaharan, A., Langford, B., Lewis, A.C., Lim, S.F., MacDonald, S.M., Mahajan, A.S., Malpass, S., McFiggans, G., Mills, G., Misztal, P., Moller, S., Monks, P.S., Nemitz, E., Nicolas-Perea, V., Oetjen, H., Oram, D.E., Palmer, P.I., Phillips, G.J., Pike, R., Plane, J.M.C., Pugh, T., Pyle, J.A., Reeves, C.E., Robinson, N.H., Stewart, David John, Stone, D., Whalley, L.K., and Yang, X.
- Abstract
In April–July 2008, intensive measurements were made of atmospheric composition and chemistry in Sabah, Malaysia, as part of the "Oxidant and particle photochemical processes above a South-East Asian tropical rainforest" (OP3) project. Fluxes and concentrations of trace gases and particles were made from and above the rainforest canopy at the Bukit Atur Global Atmosphere Watch station and at the nearby Sabahmas oil palm plantation, using both ground-based and airborne measurements. Here, the measurement and modelling strategies used, the characteristics of the sites and an overview of data obtained are described. Composition measurements show that the rainforest site was not significantly impacted by anthropogenic pollution, and this is confirmed by satellite retrievals of NO2 and HCHO. The dominant modulators of atmospheric chemistry at the rainforest site were therefore emissions of BVOCs and soil emissions of reactive nitrogen oxides. At the observed BVOC:NOx volume mixing ratio (~100 pptv/pptv), current chemical models suggest that daytime maximum OH concentrations should be ca. 105 radicals cm−3, but observed OH concentrations were an order of magnitude greater than this. We confirm, therefore, previous measurements that suggest that an unexplained source of OH must exist above tropical rainforest and we continue to interrogate the data to find explanations for this.
- Published
- 2010
20. The impact of polar stratospheric ozone loss on southern hemisphere stratospheric circulation and climate
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Keeble, J., Braesicke, P., Abraham, N.L., Roscoe, H.K., Pyle, J.A., Keeble, J., Braesicke, P., Abraham, N.L., Roscoe, H.K., and Pyle, J.A.
- Abstract
The impact of polar stratospheric ozone loss resulting from chlorine activation on polar stratospheric clouds is examined using a pair of model integrations run with the fully coupled chemistry climate model UM-UKCA. Suppressing chlorine activation through heterogeneous reactions is found to produce modelled ozone differences consistent with observed ozone differences between the present and pre-ozone hole period. Statistically significant high latitude Southern Hemisphere (SH) ozone loss begins in August and peaks in October-November, with >75% of ozone destroyed at 50 hPa. Associated with this ozone destruction is a >12 K decrease of the lower polar stratospheric temperatures and an increase of >6 K in the upper stratosphere. The heating components of this temperature change are diagnosed and it is found that the temperature dipole is the result of decreased shortwave heating in the lower stratosphere and increased dynamical heating in the upper stratosphere. The cooling of the polar lower stratosphere leads, through thermal wind balance, to an acceleration of the polar vortex and delays its breakdown by ~2 weeks. A link between lower stratospheric zonal wind speed, the vertical component of the EP flux, Fz, and the residual mean vertical circulation, w*, is identified. In December and January, increased westerly winds lead to increases in Fz, associated with an increase in tropopause height. The resulting increase in wavebreaking leads to enhanced downwelling/reduced upwelling over the polar cap. Many of the stratospheric signals modelled in this study propagate down to the troposphere, and lead to significant surface changes in December.
- Published
- 2014
21. Ozone trends at northern mid- and high latitudes – A European perspective
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Harris, N.R.P. Kyrã, E. Staehelin, J. Brunner, D. Andersen, S.-B. Godin-Beekmann, S. Dhomse, S. Hadjinicolaou, P. Hansen, G. Isaksen, I. Jrrar, A. Karpetchko, A. Kivi, R. Knudsen, B. Krizan, P. Lastovicka, J. Maeder, J. Orsolini, Y. Pyle, J.A. Rex, M. Vanicek, K. Weber, M. Wohltmann, I. Zanis, P. Zerefos, C.
- Abstract
The EU CANDIDOZ project investigated the chemical and dynamical influences on decadal ozone trends focusing on the Northern Hemisphere. High quality long-term ozone data sets, satellite-based as well as ground-based, and the long-term meteorological reanalyses from ECMWF and NCEP are used together with advanced multiple regression models and atmospheric models to assess the relative roles of chemistry and transport in stratospheric ozone changes. This overall synthesis of the individual analyses in CANDIDOZ shows clearly one common feature in the NH mid latitudes and in the Arctic: an almost monotonic negative trend from the late 1970s to the mid 1990s followed by an increase. In most trend studies, the Equivalent Effective Stratospheric Chlorine (EESC) which peaked in 1997 as a consequence of the Montreal Protocol was observed to describe ozone loss better than a simple linear trend. Furthermore, all individual analyses point to changes in dynamical drivers, such as the residual circulation (responsible for the meridional transport of ozone into middle and high latitudes) playing a key role in the observed turnaround. The changes in ozone transport are associated with variations in polar chemical ozone loss via heterogeneous ozone chemistry on PSCs (polar stratospheric clouds). Synoptic scale processes as represented by the new equivalent latitude proxy, by conventional tropopause altitude or by 250 hPa geopotential height have also been successfully linked to the recent ozone increases in the lowermost stratosphere. These show significant regional variation with a large impact over Europe and seem to be linked to changes in tropospheric climate patterns such as the North Atlantic Oscillation. Some influence in recent ozone increases was also attributed to the rise in solar cycle number 23. Changes from the late 1970s to the mid 1990s were found in a number of characteristics of the Arctic vortex. However, only one trend was found when more recent years are also considered, namely the tendency for cold winters to become colder.
- Published
- 2008
22. Strong influence of lowermost stratospheric ozone on lower tropospheric background ozone changes over Europe
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Ordóñez, C. Brunner, D. Staehelin, J. Hadjinicolaou, P. Pyle, J.A. Jonas, M. Wernli, H. Prévot, A.S.H.
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Using ozone measurements from two sounding sites and two high-altitude stations in Central Europe, we show evidence for a dominant influence of changes in lowermost stratospheric ozone on the variability and overall upward trend of background ozone in the lower troposphere (3000-3500 m asl) during the 1992-2004 period. Numerical simulations with a stratospheric chemistry transport model suggest that changes in lower stratospheric ozone were driven by dynamics rather than by changes in stratospheric chlorine loading. In addition, Lagrangian model simulations indicate that changes in downward transport of ozone from the stratosphere into the troposphere were dominated by changes in lowermost stratospheric ozone concentrations rather than by variations of cross-tropopause air mass transport. This suggests that the positive ozone trends and concentration anomalies in the lower free troposphere over Europe during the 1990s were likely to a large extent due to enhanced stratospheric ozone contributions, particularly in winter-spring. Copyright 2007 by the American Geophysical Union.
- Published
- 2007
23. The impact of meteorology on the interannual growth rate of atmospheric methane
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Warwick, N.J., Bekki, S., Law, K.S., Nisbet, E.G., and Pyle, J.A.
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Meteorology ,troposphere ,Research Groups and Centres\Earth Sciences\Geochemistry ,methane ,Faculty of Science\Earth Sciences ,Research Groups and Centres\Earth Sciences\Ancient and Modern Earth Systems - Abstract
The impact of interannual changes in meteorology on the local and global growth rates of atmospheric methane is assessed in a nineteen year simulation using a tropospheric chemical transport model forced by ECMWF meteorological analyses from 1980 to 1998. A very simple CH4 chemistry scheme has been implemented, using prescribed OH fields. There are no interannual variations in modeled methane emissions or in the OH fields, so any changes in the modeled growth rate arise from changes in meteorology. The methane simulation shows significant interannual variability at both local and global scales. The local scale variability is comparable in magnitude to the interannual variability found in surface observations and shows some clear correlation with observed changes in growth rates. This suggests that, even over interannual timescales, meteorology could be important in driving the interannual fluctuations of atmospheric methane at the surface.
- Published
- 2003
24. A global model study of the impact of land-use change in Borneo on atmospheric composition
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Warwick, N.J., Archibald, A.T., Ashworth, K., Dorsey, J., Edwards, P.M., Heard, D.E., Langford, B., Lee, J., Misztal, P.K., Whalley, L K., Pyle, J.A., Warwick, N.J., Archibald, A.T., Ashworth, K., Dorsey, J., Edwards, P.M., Heard, D.E., Langford, B., Lee, J., Misztal, P.K., Whalley, L K., and Pyle, J.A.
- Abstract
In this study, we use a high resolution version of the Cambridge p-TOMCAT model, along with data collected during the 2008 NERC-funded Oxidant and Particle Photochemical Processes (OP3) project, to examine the potential impact of the expansion of oil palm in Borneo on air quality and atmospheric composition. Several model emission scenarios are run for the OP3 measurement period, incorporating emissions from both global datasets and local flux measurements. Isoprene fluxes observed at a forest site during OP3 were considerably less than fluxes calculated using the MEGAN model. Incorporating the observed isoprene fluxes into p-TOMCAT substantially improved the comparison between modelled and observed isoprene surface mixing ratios and OH concentrations relative to using the MEGAN emissions. If both observed isoprene fluxes and HOx recycling chemistry were included, the ability of the model to capture diurnal variations in isoprene and OH was further improved. However, a similar improvement was also achieved using a~standard chemical mechanism without HOx recycling, by fixing boundary layer isoprene concentrations over Borneo to follow the OP3 observations. Further model simulations, considering an extreme scenario with all of Borneo converted to oil palm plantation, were run to determine the maximum atmospheric impact of land use change in Borneo. In these simulations, the level of nitrogen oxides was found to be critical. If only isoprene emissions from oil palm are considered, then large scale conversion to oil palm produced a decrease in monthly mean surface ozone of up to ~20%. However, if related changes in NOx emissions from fertilisation, industrial processing and transport are also included then ozone increases of up to ~70% were calculated. Although the largest changes occurred locally, the model also calculated significant regional changes of O3, OH and other species downwind of Borneo and in the free troposphere.
- Published
- 2013
25. A Lagrangian model of air-mass photochemistry and mixing using a trajectory ensemble: the Cambridge Tropospheric Trajectory model of Chemistry And Transport (CiTTyCAT) version 4.2
- Author
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Pugh, T.A.M., Cain, M., Methven, J., Wild, O., Arnold, S.R., Real, E., Law, K.S., Emmerson, K.M., Owen, S.M., Pyle, J.A., Hewitt, C.N., MacKenzie, A.R., Pugh, T.A.M., Cain, M., Methven, J., Wild, O., Arnold, S.R., Real, E., Law, K.S., Emmerson, K.M., Owen, S.M., Pyle, J.A., Hewitt, C.N., and MacKenzie, A.R.
- Abstract
A Lagrangian model of photochemistry and mixing is described (CiTTyCAT, stemming from the Cambridge Tropospheric Trajectory model of Chemistry And Transport), which is suitable for transport and chemistry studies throughout the troposphere. Over the last five years, the model has been developed in parallel at several different institutions and here those developments have been incorporated into one "community" model and documented for the first time. The key photochemical developments include a new scheme for biogenic volatile organic compounds and updated emissions schemes. The key physical development is to evolve composition following an ensemble of trajectories within neighbouring air-masses, including a simple scheme for mixing between them via an evolving "background profile", both within the boundary layer and free troposphere. The model runs along trajectories pre-calculated using winds and temperature from meteorological analyses. In addition, boundary layer height and precipitation rates, output from the analysis model, are interpolated to trajectory points and used as inputs to the mixing and wet deposition schemes. The model is most suitable in regimes when the effects of small-scale turbulent mixing are slow relative to advection by the resolved winds so that coherent air-masses form with distinct composition and strong gradients between them. Such air-masses can persist for many days while stretching, folding and thinning. Lagrangian models offer a useful framework for picking apart the processes of air-mass evolution over inter-continental distances, without being hindered by the numerical diffusion inherent to global Eulerian models. The model, including different box and trajectory modes, is described and some output for each of the modes is presented for evaluation. The model is available for download from a Subversion-controlled repository by contacting the corresponding authors.
- Published
- 2012
26. The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality
- Author
-
Pyle, J.A., Warwick, N.J., Harris, N.R.P., Abas, Mohd Radzi, Archibald, A.T., Ashfold, M.J., Ashworth, K., Barkley, Michael P., Carver, G.D., Chance, K., Dorsey, J.R., Fowler, D., Gonzi, S., Gostlow, B., Hewitt, C.N., Kurosu, T.P., Lee, J.D., Langford, S.B., Mills, G., Moller, S., MacKenzie, A.R., Manning, A.J., Misztal, P., Nadzir, Mohd Shahrul Mohd, Nemitz, E., Newton, H.M., O'Brien, L.M., Ong, Simon, Oram, D., Palmer, P.I., Peng, Leong Kok, Phang, Siew Moi, Pike, R., Pugh, T.A.M., Rahman, Noorsaadah Abdul, Robinson, A.D., Sentian, J., Samah, Azizan Abu, Skiba, U., Ung, Huan Eng, Yong, Sei Eng, Young, P.J., Pyle, J.A., Warwick, N.J., Harris, N.R.P., Abas, Mohd Radzi, Archibald, A.T., Ashfold, M.J., Ashworth, K., Barkley, Michael P., Carver, G.D., Chance, K., Dorsey, J.R., Fowler, D., Gonzi, S., Gostlow, B., Hewitt, C.N., Kurosu, T.P., Lee, J.D., Langford, S.B., Mills, G., Moller, S., MacKenzie, A.R., Manning, A.J., Misztal, P., Nadzir, Mohd Shahrul Mohd, Nemitz, E., Newton, H.M., O'Brien, L.M., Ong, Simon, Oram, D., Palmer, P.I., Peng, Leong Kok, Phang, Siew Moi, Pike, R., Pugh, T.A.M., Rahman, Noorsaadah Abdul, Robinson, A.D., Sentian, J., Samah, Azizan Abu, Skiba, U., Ung, Huan Eng, Yong, Sei Eng, and Young, P.J.
- Abstract
We present results fromtheOP3 campaign in Sabah during 2008 that allowus to study the impact of local emission changes over Borneo on atmospheric composition at the regional andwider scale. OP3 constituent data provide an important constraint onmodel performance.Treatment of boundary layer processes is highlighted as an important area of model uncertainty.Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South EastAsia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NOx emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.
- Published
- 2011
27. The atmospheric chemistry of trace gases and particulate matter emitted by different land uses in Borneo
- Author
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MacKenzie, A.R., Langford, B., Pugh, T.A.M., Robinson, N., Misztal, P.K., Heard, D.E., Lee, J.D., Lewis, A.C., Jones, C.E., Hopkins, J.R., Phillips, G., Monks, P.S., Karunaharan, A., Hornsby, K.E., Nicolas-Perea, V., Coe, H., Gabey, A.M., Gallagher, M.W., Whalley, L.K., Edwards, P.M., Evans, M.J., Stone, D., Ingham, T., Commane, R., Furneaux, K.L., McQuaid, J.B., Nemitz, E., Seng, Yap Kok, Fowler, D., Pyle, J.A., Hewitt, C.N., MacKenzie, A.R., Langford, B., Pugh, T.A.M., Robinson, N., Misztal, P.K., Heard, D.E., Lee, J.D., Lewis, A.C., Jones, C.E., Hopkins, J.R., Phillips, G., Monks, P.S., Karunaharan, A., Hornsby, K.E., Nicolas-Perea, V., Coe, H., Gabey, A.M., Gallagher, M.W., Whalley, L.K., Edwards, P.M., Evans, M.J., Stone, D., Ingham, T., Commane, R., Furneaux, K.L., McQuaid, J.B., Nemitz, E., Seng, Yap Kok, Fowler, D., Pyle, J.A., and Hewitt, C.N.
- Abstract
We report measurements of atmospheric composition over a tropical rainforest and over a nearby oil palm plantation in Sabah, Borneo. The primary vegetation in each of the two landscapes emits very different amounts and kinds of volatile organic compounds (VOCs), resulting in distinctive VOC fingerprints in the atmospheric boundary layer for both landscapes. VOCs over the Borneo rainforest are dominated by isoprene and its oxidation products, with a significant additional contribution from monoterpenes. Rather than consuming the main atmospheric oxidant, OH, these high concentrations of VOCs appear to maintain OH, as has been observed previously over Amazonia. The boundary-layer characteristics and mixing ratios of VOCs observed over the Borneo rainforest are different to those measured previously over Amazonia. Compared with the Bornean rainforest, air over the oil palm plantation contains much more isoprene, monoterpenes are relatively less important, and the flower scent, estragole, is prominent. Concentrations of nitrogen oxides are greater above the agro-industrial oil palm landscape than over the rainforest, and this leads to changes in some secondary pollutant mixing ratios (but not, currently, differences in ozone). Secondary organic aerosol over both landscapes shows a significant contribution from isoprene. Primary biological aerosol dominates the super-micrometre aerosol over the rainforest and is likely to be sensitive to land-use change, since the fungal source of the bioaerosol is closely linked to above-ground biodiversity.
- Published
- 2011
28. In search of an ice core signal to differentiate between source-driven and sink-driven changes in atmospheric methane
- Author
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Levine, J.G., Wolff, E.W., Jones, A.E., Hutterli, M.A., Wild, O., Carver, G.D., Pyle, J.A., Levine, J.G., Wolff, E.W., Jones, A.E., Hutterli, M.A., Wild, O., Carver, G.D., and Pyle, J.A.
- Abstract
The concentration of atmospheric methane increased from around 360 ppbv at the last glacial maximum (∼20 ka before present) to about 700 ppbv in the pre-industrial era (∼200 years before present). The sources and/or sinks of methane must therefore have changed during this period; however, the relative sizes of the source- and sink-driven changes in methane concentration remain uncertain. We take the first “bottom-up” approach to identifying any chemical signals preserved in the ice record that could help us to determine these. Using an atmospheric chemistry-transport model, we explore the effects of source- and sink-driven changes in methane on a wide range of chemical species in the Antarctic boundary layer. Though we identify several potentially useful atmospheric signals, a simple and robust constraint on the sizes of the source- and sink-driven changes cannot be readily identified, owing to their preservation in the ice, limitations to the information they hold, and/or ambiguity surrounding their interpretation. This includes the mass-independent fractionation of oxygen isotopes in sulfates, and the concentration of formaldehyde, in which there has been considerable interest. Our exploration is confined to a domain in which NOx emissions and climate remain constant. However, given the uncertainties associated with the changes in these factors, we would anticipate that their inclusion would make it harder still to identify a robust signal. Finally, though formaldehyde cannot provide this, we propose how it might be used to synchronize the gas- and aqueous-phase Antarctic ice records and thus determine the relative phasing of glacial-interglacial changes in Southern Hemisphere CO2 and temperature.
- Published
- 2011
29. Nitrogen management is essential to prevent tropic oil palm plantations from causing ground level ozone pollution
- Author
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Hewitt, C.N., MacKenzie, A.R., Di Carlo, P., Di Marco, C. F., Dorsey, J.R., Evans, M., Fowler, D., Gallagher, M.W., Hopkins, J.R., Jones, C.E., Langford, B., Lee, J.D., Lewis, A.C., Lim, S.F., McQuaid, J., Misztal, P., Moller, S.J., Monks, P.S., Nemitz, E., Oram, D.E., Owen, S.M., Phillips, G.J., Pugh, T.A.M., Pyle, J.A., Reeves, C.E., Ryder, J., Siong, J., Skiba, U., Stewart, D.J., Hewitt, C.N., MacKenzie, A.R., Di Carlo, P., Di Marco, C. F., Dorsey, J.R., Evans, M., Fowler, D., Gallagher, M.W., Hopkins, J.R., Jones, C.E., Langford, B., Lee, J.D., Lewis, A.C., Lim, S.F., McQuaid, J., Misztal, P., Moller, S.J., Monks, P.S., Nemitz, E., Oram, D.E., Owen, S.M., Phillips, G.J., Pugh, T.A.M., Pyle, J.A., Reeves, C.E., Ryder, J., Siong, J., Skiba, U., and Stewart, D.J.
- Abstract
More than half the world's rainforest has been lost to agriculture since the Industrial Revolution. Among the most widespread tropical crops is oil palm (Elaeis guineensis): global production now exceeds 35 million tonnes per year. In Malaysia, for example, 13% of land area is now oil palm plantation, compared with 1% in 1974. There are enormous pressures to increase palm oil production for food, domestic products, and, especially, biofuels. Greater use of palm oil for biofuel production is predicated on the assumption that palm oil is an “environmentally friendly” fuel feedstock. Here we show, using measurements and models, that oil palm plantations in Malaysia directly emit more oxides of nitrogen and volatile organic compounds than rainforest. These compounds lead to the production of ground-level ozone (O3), an air pollutant that damages human health, plants, and materials, reduces crop productivity, and has effects on the Earth's climate. Our measurements show that, at present, O3 concentrations do not differ significantly over rainforest and adjacent oil palm plantation landscapes. However, our model calculations predict that if concentrations of oxides of nitrogen in Borneo are allowed to reach those currently seen over rural North America and Europe, ground-level O3 concentrations will reach 100 parts per billion (109) volume (ppbv) and exceed levels known to be harmful to human health. Our study provides an early warning of the urgent need to develop policies that manage nitrogen emissions if the detrimental effects of palm oil production on air quality and climate are to be avoided.
- Published
- 2009
30. The sensitivity of Western European NO2 columns to interannual variability of meteorology and emissions: A model - GOME study
- Author
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Savage, N.H., Pyle, J.A., Braesicke, P., Wittrock, F., Richter, A., Nüß, H., Burrows, J.P., Schultz, M.G., Pulles, M.P.J., Bolscher, M. van het, Savage, N.H., Pyle, J.A., Braesicke, P., Wittrock, F., Richter, A., Nüß, H., Burrows, J.P., Schultz, M.G., Pulles, M.P.J., and Bolscher, M. van het
- Abstract
Interannual variability (IAV) in tropospheric species concentrations can be driven by variability in emissions, chemistry, transport and UV radiation. In a 3D CTM study we have found good agreement between the IAV of NO2 columns observed by the GOME satellite instrument and model simulations over Western Europe from 1996 to 2000. We find that meteorological variability is an important factor during this period. Averaged 10 m wind speeds from the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis are a good proxy for the overall meteorology driving the IAV during the studied period of 1996-2000. Copyright © 2008 Royal Meteorological Society.
- Published
- 2008
31. Latitudinal variation of the effect of aviation NOx emissions on atmospheric ozone and methane and related climate metrics
- Author
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Köhler, M.O., primary, Rädel, G., additional, Shine, K.P., additional, Rogers, H.L., additional, and Pyle, J.A., additional
- Published
- 2013
- Full Text
- View/download PDF
32. Modelling and Measurement Studies of Northern Hemisphere Ozone Loss within the SESAME Campaign
- Author
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Pyle, J.A., Platt, U., Renger, W., Hausamann, D., Blohm, C., O'Neill, A., and Swinbank, S.
- Subjects
Lidar ,PSC ,stratosphärisches Ozon - Published
- 1997
33. Multimodel simulations of carbon monoxide: Comparison with observations and projected near-future changes
- Author
-
Shindell, D.T., Faluvegi, G., Stevenson, D.S., Krol, M.C., Emmons, L.K., Lamarque, J.F., Petron, G., Dentener, F.J., Ellingsen, K., Schultz, M.G., Wild, O., Amann, M., Atherton, C.S., Bergmann, D.J., Bey, I., Butler, T., Cofala, J., Collins, W.J., Derwent, R.G., Doherty, R.M., Drevet, J., Eskes, H.J., Fiore, A.M., Gauss, M., Hauglustaine, D.A., Horowitz, L.W., Isaksen, I.S.A., Lawrence, M.G., Montanaro, V., Muller, J.F., Pitari, G., Prather, M.J., Pyle, J.A., Rast, S., Rodriguez, J.M., Sanderson, M.G., Savage, N.H., Strahan, S.E., Sudo, K., Szopa, S., Unger, N., van Noije, T.P.C., Zeng, G., Shindell, D.T., Faluvegi, G., Stevenson, D.S., Krol, M.C., Emmons, L.K., Lamarque, J.F., Petron, G., Dentener, F.J., Ellingsen, K., Schultz, M.G., Wild, O., Amann, M., Atherton, C.S., Bergmann, D.J., Bey, I., Butler, T., Cofala, J., Collins, W.J., Derwent, R.G., Doherty, R.M., Drevet, J., Eskes, H.J., Fiore, A.M., Gauss, M., Hauglustaine, D.A., Horowitz, L.W., Isaksen, I.S.A., Lawrence, M.G., Montanaro, V., Muller, J.F., Pitari, G., Prather, M.J., Pyle, J.A., Rast, S., Rodriguez, J.M., Sanderson, M.G., Savage, N.H., Strahan, S.E., Sudo, K., Szopa, S., Unger, N., van Noije, T.P.C., and Zeng, G.
- Abstract
We analyze present-day and future carbon monoxide (CO) simulations in 26 state-of-the-art atmospheric chemistry models run to study future air quality and climate change. In comparison with near-global satellite observations from the MOPITT instrument and local surface measurements, the models show large underestimates of Northern Hemisphere (NH) extratropical CO, while typically performing reasonably well elsewhere. The results suggest that year-round emissions, probably from fossil fuel burning in east Asia and seasonal biomass burning emissions in south-central Africa, are greatly underestimated in current inventories such as IIASA and EDGAR3.2. Variability among models is large, likely resulting primarily from intermodel differences in representations and emissions of nonmethane volatile organic compounds (NMVOCs) and in hydrologic cycles, which affect OH and soluble hydrocarbon intermediates. Global mean projections of the 2030 CO response to emissions changes are quite robust. Global mean midtropospheric (500 hPa) CO increases by 12.6 +/- 3.5 ppbv (16%) for the high-emissions (A2) scenario, by 1.7 +/- 1.8 ppbv (2%) for the midrange (CLE) scenario, and decreases by 8.1 +/- 2.3 ppbv (11%) for the low-emissions (MFR) scenario. Projected 2030 climate changes decrease global 500 hPa CO by 1.4 +/- 1.4 ppbv. Local changes can be much larger. In response to climate change, substantial effects are seen in the tropics, but intermodel variability is quite large. The regional CO responses to emissions changes are robust across models, however. These range from decreases of 10-20 ppbv over much of the industrialized NH for the CLE scenario to CO increases worldwide and year-round under A2, with the largest changes over central Africa (20-30 ppbv), southern Brazil (20-35 ppbv) and south and east Asia (30-70 ppbv). The trajectory of future emissions thus has the potential to profoundly affect air quality over most of the world's populated areas.
- Published
- 2006
34. Multi-model ensemble simulations of troposheric NO2 compared with GOME retrievals for the year 2000
- Author
-
van Noije, T.P.C., Eskes, H.J., Dentener, F.J., Stevenson, D.S., Ellingsen, K., Schultz, M.G., Wild, O., Amann, M., Atherton, C.S., Bergmann, D., Bey, I., Boersma, K.F., Butler, T., Cofala, J., Drevet, J., Fiore, A.M., Gauss, M., Hauglustaine, D.A., Horowitz, L.W., Isaksen, I.S.A., Krol, M.C., Lamarque, J.F., Lawrence, M.G., Martin, R.V., Montanaro, V., Muller, J.F., Pitari, G., Prather, M.J., Pyle, J.A., Richter, A., Rodriguez, J.M., Savage, N.H., Strahan, S.E., Sudo, K., Szopa, S., van Roozendael, M., van Noije, T.P.C., Eskes, H.J., Dentener, F.J., Stevenson, D.S., Ellingsen, K., Schultz, M.G., Wild, O., Amann, M., Atherton, C.S., Bergmann, D., Bey, I., Boersma, K.F., Butler, T., Cofala, J., Drevet, J., Fiore, A.M., Gauss, M., Hauglustaine, D.A., Horowitz, L.W., Isaksen, I.S.A., Krol, M.C., Lamarque, J.F., Lawrence, M.G., Martin, R.V., Montanaro, V., Muller, J.F., Pitari, G., Prather, M.J., Pyle, J.A., Richter, A., Rodriguez, J.M., Savage, N.H., Strahan, S.E., Sudo, K., Szopa, S., and van Roozendael, M.
- Abstract
We present a systematic comparison of tropospheric NO2 from 17 global atmospheric chemistry models with three state-of-the-art retrievals from the Global Ozone Monitoring Experiment (GOME) for the year 2000. The models used constant anthropogenic emissions from IIASA/EDGAR3.2 and monthly emissions from biomass burning based on the 1997¿2002 average carbon emissions from the Global Fire Emissions Database (GFED). Model output is analyzed at 10:30 local time, close to the overpass time of the ERS-2 satellite, and collocated with the measurements to account for sampling biases due to incomplete spatiotemporal coverage of the instrument. We assessed the importance of different contributions to the sampling bias: correlations on seasonal time scale give rise to a positive bias of 30¿50% in the retrieved annual means over regions dominated by emissions from biomass burning. Over the industrial regions of the eastern United States, Europe and eastern China the retrieved annual means have a negative bias with significant contributions (between ¿25% and +10% of the NO2 column) resulting from correlations on time scales from a day to a month. We present global maps of modeled and retrieved annual mean NO2 column densities, together with the corresponding ensemble means and standard deviations for models and retrievals. The spatial correlation between the individual models and retrievals are high, typically in the range 0.81¿0.93 after smoothing the data to a common resolution. On average the models underestimate the retrievals in industrial regions, especially over eastern China and over the Highveld region of South Africa, and overestimate the retrievals in regions dominated by biomass burning during the dry season. The discrepancy over South America south of the Amazon disappears when we use the GFED emissions specific to the year 2000. The seasonal cycle is analyzed in detail for eight different continental regions. Over regions dominated by biomass burning, the timing of
- Published
- 2006
35. Multimodel ensemble simulations of present-day and near-future tropospheric ozone
- Author
-
Stevenson, D.S., Dentener, F.J., Schultz, M.G., Ellingsen, K., van Noije, T.P.C., Wild, O., Zeng, G., Amann, M., Atherton, C.S., Bell, N., Bergmann, D.J., Bey, I., Butler, T., Cofala, J., Collins, W.J., Derwent, R.G., Doherty, R.M., Drevet, J., Eskes, H.J., Fiore, A.M., Gauss, M., Hauglustaine, D.A., Horowitz, L.W., Isaksen, I.S.A., Krol, M.C., Lamarque, J.F., Lawrence, M.G., Montanaro, V., Muller, J.F., Pitari, G., Prather, M.J., Pyle, J.A., Rast, S., Rodriguez, J.M., Sanderson, M.G., Savage, N.H., Shindell, D.T., Strahan, S.E., Sudo, K., Szopa, S., Stevenson, D.S., Dentener, F.J., Schultz, M.G., Ellingsen, K., van Noije, T.P.C., Wild, O., Zeng, G., Amann, M., Atherton, C.S., Bell, N., Bergmann, D.J., Bey, I., Butler, T., Cofala, J., Collins, W.J., Derwent, R.G., Doherty, R.M., Drevet, J., Eskes, H.J., Fiore, A.M., Gauss, M., Hauglustaine, D.A., Horowitz, L.W., Isaksen, I.S.A., Krol, M.C., Lamarque, J.F., Lawrence, M.G., Montanaro, V., Muller, J.F., Pitari, G., Prather, M.J., Pyle, J.A., Rast, S., Rodriguez, J.M., Sanderson, M.G., Savage, N.H., Shindell, D.T., Strahan, S.E., Sudo, K., and Szopa, S.
- 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 CO2 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 stratos
- Published
- 2006
36. Modelling and Measurement Studies of Northern Hemisphere Ozone Loss within the SESAM Campaign. A Study of Hemispheric Scale Processes Affecting Ozone
- Author
-
Pyle, J.A., Platt, U., Renger, W., Blom, C., O'Neill, A., Hausamann, D., and Swinbank, R.
- Subjects
ozone ,OLEX-Lidar ,SESAME - Published
- 1996
37. Early Modelling Results from the SESAME and ASHOE Campaigns
- Author
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Pyle, J.A.(1), Chipperfield, M.P. (1), Kilbane-Dave, I. (1), Lee, A.M. (1), Stimpfle, R.M. (2), Kohn, D. (2), Renger, W., and Waters, J.W. (3)
- Subjects
Polar Vortex ,Ozon ,Stratosphäre ,SESAME - Published
- 1995
38. Effects of Climate-induced Changes in Isoprene Emissions after the eruption of Mount Pinatubo
- Author
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Telford, P.J., primary, Lathière, J., additional, Abraham, N.L., additional, Archibald, A.T., additional, Braesicke, P., additional, Johnson, C.E., additional, Morgenstern, O., additional, O’Connor, F.M., additional, Pike, R.C., additional, Wild, O., additional, Young, P.J., additional, Beerling, D.J., additional, Hewitt, C.N., additional, and Pyle, J.A., additional
- Published
- 2011
- Full Text
- View/download PDF
39. Surface layer measurements of turbulence
- Author
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Holton, J.R., Curry, J.A., Pyle, J.A., Jensen, N.O., Holton, J.R., Curry, J.A., Pyle, J.A., and Jensen, N.O.
- Published
- 2003
40. Future aircraft and global ozone
- Author
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Bekki, S., Toumi, R., Pyle, J.A., and Jones, A.E.
- Subjects
Airplanes -- Innovations ,Ozone layer -- Protection and preservation ,Stratosphere -- Analysis ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Published
- 1991
41. Sensitivity of dynamics and ozone to different representations of SSTs in the Unified Model
- Author
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Braesicke, P., primary and Pyle, J.A., additional
- Published
- 2004
- Full Text
- View/download PDF
42. Modelling NOx from lightning and its impact on global chemical fields
- Author
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Stockwell, D.Z., primary, Giannakopoulos, C., additional, Plantevin, P.-H., additional, Carver, G.D., additional, Chipperfield, M.P., additional, Law, K.S., additional, Pyle, J.A., additional, Shallcross, D.E., additional, and Wang, K.-Y., additional
- Published
- 1999
- Full Text
- View/download PDF
43. Model studies of dynamics, chemistry and transport in the Antarctic and Arctic stratosphere
- Author
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Heywood, R.B., McIntyre, M.E., Pyle, J.A., Heywood, R.B., McIntyre, M.E., and Pyle, J.A.
- Published
- 1993
44. Antarctica and environmental change. Proceedings of a Royal Society discussion meeting. May 1992
- Author
-
Drewry, D.J., Laws, R.M., Pyle, J.A., Drewry, D.J., Laws, R.M., and Pyle, J.A.
- Published
- 1992
45. Stratospheric ozone 1990
- Author
-
Pyle, J.A., Cox, R.A., Farman, J., Gray, L.J., Harries, J., Jones, R.L., O'Neill, A., Penkett, S.A., Roscoe, H.K., Warrilow, D.A., Pyle, J.A., Cox, R.A., Farman, J., Gray, L.J., Harries, J., Jones, R.L., O'Neill, A., Penkett, S.A., Roscoe, H.K., and Warrilow, D.A.
- Published
- 1990
46. Lessons for the future from coordinated European stratospheric campaigns
- Author
-
Pyle, J.A., primary and Harris, N.R.P., additional
- Published
- 1995
- Full Text
- View/download PDF
47. A three-dimensional model study of chemistry in the lower stratosphere
- Author
-
Lary, D., primary, Carver, G., additional, and Pyle, J.A., additional
- Published
- 1993
- Full Text
- View/download PDF
48. On the limitation of steady-state expressions as tests of photochemical theory of the stratosphere
- Author
-
Toumi, R., primary and Pyle, J.A., additional
- Published
- 1992
- Full Text
- View/download PDF
49. Authors' reply
- Author
-
Law, K.S., primary and Pyle, J.A., additional
- Published
- 1992
- Full Text
- View/download PDF
50. Modelling the response of tropospheric trace species to changing source gas concentrations
- Author
-
Law, K.S, primary and Pyle, J.A, additional
- Published
- 1991
- Full Text
- View/download PDF
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