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Keller CA, Knowland KE, Duncan BN, Liu J, Anderson DC, Das S, Lucchesi RA, Lundgren EW, Nicely JM, Nielsen E, Ott LE, Saunders E, Strode SA, Wales PA, Jacob DJ, Pawson S. Description of the NASA GEOS Composition Forecast Modeling System GEOS-CF v1.0. JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2021; 13:e2020MS002413. [PMID: 34221240 PMCID: PMC8244029 DOI: 10.1029/2020ms002413] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/18/2021] [Accepted: 03/16/2021] [Indexed: 05/11/2023]
Abstract
The Goddard Earth Observing System composition forecast (GEOS-CF) system is a high-resolution (0.25°) global constituent prediction system from NASA's Global Modeling and Assimilation Office (GMAO). GEOS-CF offers a new tool for atmospheric chemistry research, with the goal to supplement NASA's broad range of space-based and in-situ observations. GEOS-CF expands on the GEOS weather and aerosol modeling system by introducing the GEOS-Chem chemistry module to provide hindcasts and 5-days forecasts of atmospheric constituents including ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and fine particulate matter (PM2.5). The chemistry module integrated in GEOS-CF is identical to the offline GEOS-Chem model and readily benefits from the innovations provided by the GEOS-Chem community. Evaluation of GEOS-CF against satellite, ozonesonde and surface observations for years 2018-2019 show realistic simulated concentrations of O3, NO2, and CO, with normalized mean biases of -0.1 to 0.3, normalized root mean square errors between 0.1-0.4, and correlations between 0.3-0.8. Comparisons against surface observations highlight the successful representation of air pollutants in many regions of the world and during all seasons, yet also highlight current limitations, such as a global high bias in SO2 and an overprediction of summertime O3 over the Southeast United States. GEOS-CF v1.0 generally overestimates aerosols by 20%-50% due to known issues in GEOS-Chem v12.0.1 that have been addressed in later versions. The 5-days forecasts have skill scores comparable to the 1-day hindcast. Model skills can be improved significantly by applying a bias-correction to the surface model output using a machine-learning approach.
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Affiliation(s)
- Christoph A. Keller
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | - K. Emma Knowland
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | | | - Junhua Liu
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | - Daniel C. Anderson
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | - Sampa Das
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | - Robert A. Lucchesi
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Science Systems and Applications, Inc.LanhamMDUSA
| | | | - Julie M. Nicely
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Earth System Science Interdisciplinary CenterUniversity of MarylandCollege ParkLanhamMDUSA
| | - Eric Nielsen
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Science Systems and Applications, Inc.LanhamMDUSA
| | | | - Emily Saunders
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Science Systems and Applications, Inc.LanhamMDUSA
| | - Sarah A. Strode
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | - Pamela A. Wales
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Universities Space Research AssociationColumbiaMDUSA
| | - Daniel J. Jacob
- School of Engineering and Applied SciencesHarvard UniversityCambridgeMAUSA
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Bruhwiler L, Basu S, Butler JH, Chatterjee A, Dlugokencky E, Kenney MA, McComiskey A, Montzka SA, Stanitski D. Observations of greenhouse gases as climate indicators. CLIMATIC CHANGE 2021; 165:12. [PMID: 33758443 PMCID: PMC7940260 DOI: 10.1007/s10584-021-03001-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Humans have significantly altered the energy balance of the Earth's climate system mainly not only by extracting and burning fossil fuels but also by altering the biosphere and using halocarbons. The 3rd US National Climate Assessment pointed to a need for a system of indicators of climate and global change based on long-term data that could be used to support assessments and this led to the development of the National Climate Indicators System (NCIS). Here we identify a representative set of key atmospheric indicators of changes in atmospheric radiative forcing due to greenhouse gases (GHGs), and we evaluate atmospheric composition measurements, including non-CO2 GHGs for use as climate change indicators in support of the US National Climate Assessment. GHG abundances and their changes over time can provide valuable information on the success of climate mitigation policies, as well as insights into possible carbon-climate feedback processes that may ultimately affect the success of those policies. To ensure that reliable information for assessing GHG emission changes can be provided on policy-relevant scales, expanded observational efforts are needed. Furthermore, the ability to detect trends resulting from changing emissions requires a commitment to supporting long-term observations. Long-term measurements of greenhouse gases, aerosols, and clouds and related climate indicators used with a dimming/brightening index could provide a foundation for quantifying forcing and its attribution and reducing error in existing indicators that do not account for complicated cloud processes.
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Affiliation(s)
| | - Sourish Basu
- NASA Goddard Space Flight Center, Greenbelt, MD USA
- Universities Space Research Association, Columbia, MD USA
| | | | - Abhishek Chatterjee
- NASA Goddard Space Flight Center, Greenbelt, MD USA
- Universities Space Research Association, Columbia, MD USA
| | | | - Melissa A. Kenney
- University of Minnesota Institute on the Environment, Saint Paul, MN USA
| | - Allison McComiskey
- Brookhaven National Laboratory, Environmental & Climate Sciences Department, Upton, NY USA
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3
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Wolfe GM, Nicely JM, St Clair JM, Hanisco TF, Liao J, Oman LD, Brune WB, Miller D, Thames A, González Abad G, Ryerson TB, Thompson CR, Peischl J, McCain K, Sweeney C, Wennberg PO, Kim M, Crounse JD, Hall SR, Ullmann K, Diskin G, Bui P, Chang C, Dean-Day J. Mapping hydroxyl variability throughout the global remote troposphere via synthesis of airborne and satellite formaldehyde observations. Proc Natl Acad Sci U S A 2019; 116:11171-11180. [PMID: 31110019 PMCID: PMC6561255 DOI: 10.1073/pnas.1821661116] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hydroxyl radical (OH) fuels tropospheric ozone production and governs the lifetime of methane and many other gases. Existing methods to quantify global OH are limited to annual and global-to-hemispheric averages. Finer resolution is essential for isolating model deficiencies and building process-level understanding. In situ observations from the Atmospheric Tomography (ATom) mission demonstrate that remote tropospheric OH is tightly coupled to the production and loss of formaldehyde (HCHO), a major hydrocarbon oxidation product. Synthesis of this relationship with satellite-based HCHO retrievals and model-derived HCHO loss frequencies yields a map of total-column OH abundance throughout the remote troposphere (up to 70% of tropospheric mass) over the first two ATom missions (August 2016 and February 2017). This dataset offers unique insights on near-global oxidizing capacity. OH exhibits significant seasonality within individual hemispheres, but the domain mean concentration is nearly identical for both seasons (1.03 ± 0.25 × 106 cm-3), and the biseasonal average North/South Hemisphere ratio is 0.89 ± 0.06, consistent with a balance of OH sources and sinks across the remote troposphere. Regional phenomena are also highlighted, such as a 10-fold OH depression in the Tropical West Pacific and enhancements in the East Pacific and South Atlantic. This method is complementary to budget-based global OH constraints and can help elucidate the spatial and temporal variability of OH production and methane loss.
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Affiliation(s)
- Glenn M Wolfe
- Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD 21228;
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771
| | - Julie M Nicely
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771
- Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20740
| | - Jason M St Clair
- Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD 21228
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771
| | - Thomas F Hanisco
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771
| | - Jin Liao
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771
- Universities Space Research Association, Columbia, MD 21046
| | - Luke D Oman
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771
| | - William B Brune
- Department of Meteorology and Atmospheric Science, Pennsylvania State University, University Park, PA 16801
| | - David Miller
- Department of Meteorology and Atmospheric Science, Pennsylvania State University, University Park, PA 16801
| | - Alexander Thames
- Department of Meteorology and Atmospheric Science, Pennsylvania State University, University Park, PA 16801
| | | | - Thomas B Ryerson
- Chemical Sciences Division, National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, Boulder, CO 80305
| | - Chelsea R Thompson
- Chemical Sciences Division, National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, Boulder, CO 80305
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309
| | - Jeff Peischl
- Chemical Sciences Division, National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, Boulder, CO 80305
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309
| | - Kathryn McCain
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309
- Global Monitoring Division, NOAA Earth System Research Laboratory, Boulder, CO 80305
| | - Colm Sweeney
- Global Monitoring Division, NOAA Earth System Research Laboratory, Boulder, CO 80305
| | - Paul O Wennberg
- Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125
| | - Michelle Kim
- Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
| | - John D Crounse
- Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
| | - Samuel R Hall
- Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80307
| | - Kirk Ullmann
- Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO 80307
| | - Glenn Diskin
- Atmospheric Composition, NASA Langley Research Center, Hampton VA 23666
| | - Paul Bui
- Atmospheric Science, NASA Ames Research Center, Moffett Field, CA 94035
| | - Cecilia Chang
- Atmospheric Science, NASA Ames Research Center, Moffett Field, CA 94035
- Bay Area Environmental Research Institute, Moffett Field, CA 94952
| | - Jonathan Dean-Day
- Atmospheric Science, NASA Ames Research Center, Moffett Field, CA 94035
- Bay Area Environmental Research Institute, Moffett Field, CA 94952
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Abstract
The hydroxyl radical (OH) is central to tropospheric chemistry, but current measurements are insufficient to assess its effects on year-to-year changes in atmospheric methane. We use a 6,000-y control simulation in a global coupled chemistry-climate model to study the natural variability of OH. We find that natural OH variability can produce (unforced) methane trends as large as the observed changes in methane over the last few decades. Additionally, we find a link between OH and La Niña. While we cannot directly measure annual global mean OH, we can use what we know about La Niña to improve our understanding of OH. This may, in turn, improve our understanding of recent methane trends. The hydroxyl radical (OH) is the primary oxidant in the troposphere, and the impact of its fluctuations on the methane budget has been disputed in recent years, however measurements of OH are insufficient to characterize global interannual fluctuations relevant for methane. Here, we use a 6,000-y control simulation of preindustrial conditions with a chemistry-climate model to quantify the natural variability in OH and internal feedbacks governing that variability. We find that, even in the absence of external forcing, maximum OH changes are 3.8 ± 0.8% over a decade, which is large in the context of the recent methane growth from 2007–2017. We show that the OH variability is not a white-noise process. A wavelet analysis indicates that OH variability exhibits significant feedbacks with the same periodicity as the El Niño–Southern Oscillation (ENSO). We find intrinsically generated modulation of the OH variability, suggesting that OH may show periods of rapid or no change in future decades that are solely due to the internal climate dynamics (as opposed to external forcings). An empirical orthogonal function analysis further indicates that ENSO is the dominant mode of OH variability, with the modulation of OH occurring primarily through lightning NOx. La Niña is associated with an increase in convection in the Tropical Pacific, which increases the simulated occurrence of lightning and allows for more OH production. Understanding this link between OH and ENSO may improve the predictability of the oxidative capacity of the troposphere and assist in elucidating the causes of current and historical trends in methane.
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5
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Abstract
The growth in global methane (CH4) concentration, which had been ongoing since the industrial revolution, stalled around the year 2000 before resuming globally in 2007. We evaluate the role of the hydroxyl radical (OH), the major CH4 sink, in the recent CH4 growth. We also examine the influence of systematic uncertainties in OH concentrations on CH4 emissions inferred from atmospheric observations. We use observations of 1,1,1-trichloroethane (CH3CCl3), which is lost primarily through reaction with OH, to estimate OH levels as well as CH3CC3 emissions, which have uncertainty that previously limited the accuracy of OH estimates. We find a 64-70% probability that a decline in OH has contributed to the post-2007 methane rise. Our median solution suggests that CH4 emissions increased relatively steadily during the late 1990s and early 2000s, after which growth was more modest. This solution obviates the need for a sudden statistically significant change in total CH4 emissions around the year 2007 to explain the atmospheric observations and can explain some of the decline in the atmospheric 13CH4/12CH4 ratio and the recent growth in C2H6 Our approach indicates that significant OH-related uncertainties in the CH4 budget remain, and we find that it is not possible to implicate, with a high degree of confidence, rapid global CH4 emissions changes as the primary driver of recent trends when our inferred OH trends and these uncertainties are considered.
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6
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Keyte IJ, Harrison RM, Lammel G. Chemical reactivity and long-range transport potential of polycyclic aromatic hydrocarbons – a review. Chem Soc Rev 2013; 42:9333-91. [DOI: 10.1039/c3cs60147a] [Citation(s) in RCA: 436] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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7
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Manning M, Reisinger A. Broader perspectives for comparing different greenhouse gases. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:1891-1905. [PMID: 21502165 DOI: 10.1098/rsta.2010.0349] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Over the last 20 years, different greenhouse gases have been compared, in the context of climate change, primarily through the concept of global warming potentials (GWPs). This considers the climate forcing caused by pulse emissions and integrated over a fixed time horizon. Recent studies have shown that uncertainties in GWP values are significantly larger than previously thought and, while past literature in this area has raised alternative means of comparison, there is not yet any clear alternative. We propose that a broader framework for comparing greenhouse gases has become necessary and that this cannot be addressed by using simple fixed exchange rates. From a policy perspective, the framework needs to be clearly aligned with the goal of climate stabilization, and we show that comparisons between gases can be better addressed in this context by the forcing equivalence index (FEI). From a science perspective, a framework for comparing greenhouse gases should also consider the full range of processes that affect atmospheric composition and how these may alter for climate stabilization at different levels. We cover a basis for a broader approach to comparing greenhouse gases by summarizing the uncertainties in GWPs, linking those to uncertainties in the FEIs consistent with stabilization, and then to a framework for addressing uncertainties in the corresponding biogeochemical processes.
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Affiliation(s)
- Martin Manning
- New Zealand Climate Change Research Institute, Victoria University of Wellington, New Zealand.
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8
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Fortems-Cheiney A, Chevallier F, Pison I, Bousquet P, Szopa S, Deeter MN, Clerbaux C. Ten years of CO emissions as seen from Measurements of Pollution in the Troposphere (MOPITT). ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jd014416] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Bousquet P, Yver C, Pison I, Li YS, Fortems A, Hauglustaine D, Szopa S, Rayner PJ, Novelli P, Langenfelds R, Steele P, Ramonet M, Schmidt M, Foster P, Morfopoulos C, Ciais P. A three-dimensional synthesis inversion of the molecular hydrogen cycle: Sources and sinks budget and implications for the soil uptake. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jd014599] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Affiliation(s)
- I. S. A. Isaksen
- Department of Geosciences, University of Oslo, 0316 Oslo, Norway
- CICERO, Centre for International Climate and Environmental Research-Oslo, 0349 Oslo, Norway
| | - S. B. Dalsøren
- CICERO, Centre for International Climate and Environmental Research-Oslo, 0349 Oslo, Norway
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11
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Montzka SA, Krol M, Dlugokencky E, Hall B, Jockel P, Lelieveld J. Small Interannual Variability of Global Atmospheric Hydroxyl. Science 2011; 331:67-9. [DOI: 10.1126/science.1197640] [Citation(s) in RCA: 249] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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12
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Bergamaschi P, Frankenberg C, Meirink JF, Krol M, Villani MG, Houweling S, Dentener F, Dlugokencky EJ, Miller JB, Gatti LV, Engel A, Levin I. Inverse modeling of global and regional CH4emissions using SCIAMACHY satellite retrievals. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2009jd012287] [Citation(s) in RCA: 247] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Millet DB, Atlas EL, Blake DR, Blake NJ, Diskin GS, Holloway JS, Hudman RC, Meinardi S, Ryerson TB, Sachse GW. Halocarbon emissions from the United States and Mexico and their global warming potential. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:1055-1060. [PMID: 19320157 DOI: 10.1021/es802146j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We use recent aircraft measurements of a comprehensive suite of anthropogenic halocarbons, carbon monoxide (CO), and related tracers to place new constraints on North American halocarbon emissions and quantify their global warming potential. Using a chemical transport model (GEOS-Chem) we find that the ensemble of observations are consistent with our prior best estimate of the U.S. anthropogenic CO source, but suggest a 30% underestimate of Mexican emissions. We develop an optimized CO emission inventory on this basis and quantify halocarbon emissions from their measured enhancements relative to CO. Emissions continue for many compounds restricted under the Montreal Protocol, and we show that halocarbons make up an important fraction of the total greenhouse gas source for both countries: our best estimate is 9% (uncertainty range 6-12%) and 32% (21-52%) of equivalent CO2 emissions for the U.S. and Mexico, respectively, on a 20 year time scale. Performance of bottom-up emission inventories is variable, with underestimates for some compounds and overestimates for others. Ongoing methylchloroform emissions are significant in the U.S. (2.8 Gg/y in 2004-2006), in contrast to bottom-up estimates (< 0.05 Gg), with implications for tropospheric OH calculations. Mexican methylchloroform emissions are minor.
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Affiliation(s)
- Dylan B Millet
- University of Minnesota, St. Paul, Minnesota 55108, USA.
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14
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Wang JS, McElroy MB, Logan JA, Palmer PI, Chameides WL, Wang Y, Megretskaia IA. A quantitative assessment of uncertainties affecting estimates of global mean OH derived from methyl chloroform observations. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jd008496] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Pollmann J, Helmig D, Hueber J, Plass-Dülmer C, Tans P. Sampling, storage, and analysis of C2–C7 non-methane hydrocarbons from the US National Oceanic and Atmospheric Administration Cooperative Air Sampling Network glass flasks. J Chromatogr A 2008; 1188:75-87. [DOI: 10.1016/j.chroma.2008.02.059] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 02/07/2008] [Accepted: 02/14/2008] [Indexed: 11/29/2022]
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17
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Atkinson R, Arey J. MECHANISMS OF THE GAS-PHASE REACTIONS OF AROMATIC HYDROCARBONS AND PAHS WITH OH AND NO3RADICALS. Polycycl Aromat Compd 2007. [DOI: 10.1080/10406630601134243] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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18
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Wilson SR, Solomon KR, Tang X. Changes in tropospheric composition and air quality due to stratospheric ozone depletion and climate change. Photochem Photobiol Sci 2007; 6:301-10. [PMID: 17344964 DOI: 10.1039/b700022g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It is well-understood that reductions in air quality play a significant role in both environmental and human health. Interactions between ozone depletion and global climate change will significantly alter atmospheric chemistry which, in turn, will cause changes in concentrations of natural and human-made gases and aerosols. Models predict that tropospheric ozone near the surface will increase globally by up to 10 to 30 ppbv (33 to 100% increase) during the period 2000 to 2100. With the increase in the amount of the stratospheric ozone, increased transport from the stratosphere to the troposphere will result in different responses in polluted and unpolluted areas. In contrast, global changes in tropospheric hydroxyl radical (OH) are not predicted to be large, except where influenced by the presence of oxidizable organic matter, such as from large-scale forest fires. Recent measurements in a relatively clean location over 5 years showed that OH concentrations can be predicted by the intensity of solar ultraviolet radiation. If this relationship is confirmed by further observations, this approach could be used to simplify assessments of air quality. Analysis of surface-level ozone observations in Antarctica suggests that there has been a significant change in the chemistry of the boundary layer of the atmosphere in this region as a result of stratospheric ozone depletion. The oxidation potential of the Antarctic boundary layer is estimated to be greater now than before the development of the ozone hole. Recent modeling studies have suggested that iodine and iodine-containing substances from natural sources, such as the ocean, may increase stratospheric ozone depletion significantly in polar regions during spring. Given the uncertainty of the fate of iodine in the stratosphere, the results may also be relevant for stratospheric ozone depletion and measurements of the influence of these substances on ozone depletion should be considered in the future. In agreement with known usage and atmospheric loss processes, tropospheric concentrations of HFC-134a, the main human-made source of trifluoroacetic acid (TFA), is increasing rapidly. As HFC-134a is a potent greenhouse gas, this increasing concentration has implications for climate change. However, the risks to humans and the environment from substances, such as TFA, produced by atmospheric degradation of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are considered minimal. Perfluoropolyethers, commonly used as industrial heat transfer fluids and proposed as chlorohydrofluorocarbon (CHFC) substitutes, show great stability to chemical degradation in the atmosphere. These substances have been suggested as substitutes for CHFCs but, as they are very persistent in the atmosphere, they may be important contributors to global warming. It is not known whether these substances will contribute significantly to global warming and its interaction with ozone depletion but they should be considered for further evaluation.
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Affiliation(s)
- S R Wilson
- Department of Chemistry, University of Wollongong, NSW 2522, Australia
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19
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Stevenson DS, Dentener FJ, Schultz MG, Ellingsen K, van Noije TPC, Wild O, Zeng G, Amann M, Atherton CS, Bell N, Bergmann DJ, Bey I, Butler T, Cofala J, Collins WJ, Derwent RG, Doherty RM, Drevet J, Eskes HJ, Fiore AM, Gauss M, Hauglustaine DA, Horowitz LW, Isaksen ISA, Krol MC, Lamarque JF, Lawrence MG, Montanaro V, Müller JF, Pitari G, Prather MJ, Pyle JA, Rast S, Rodriguez JM, Sanderson MG, Savage NH, Shindell DT, Strahan SE, Sudo K, Szopa S. Multimodel ensemble simulations of present-day and near-future tropospheric ozone. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006338] [Citation(s) in RCA: 632] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Manning MR, Lowe DC, Moss RC, Bodeker GE, Allan W. Short-term variations in the oxidizing power of the atmosphere. Nature 2005; 436:1001-4. [PMID: 16107844 DOI: 10.1038/nature03900] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 06/07/2005] [Indexed: 11/09/2022]
Abstract
The hydroxyl radical is the predominant atmospheric oxidant, responsible for removing a wide range of trace gases, including greenhouse gases, from the atmosphere. Determination of trends and variability in hydroxyl radical concentrations is critical to understanding whether the 'cleansing' properties of the atmosphere are changing. The variability in hydroxyl radical concentrations on annual to monthly timescales, however, is difficult to quantify. Here we show records of carbon monoxide containing radiocarbon (14CO), which is oxidized by hydroxyl radicals, from clean-air sites at Baring Head, New Zealand, and Scott Base, Antarctica, spanning 13 years. Using a model study, we correct for known variations in production of 14CO (refs 6, 7), allowing us to exploit this species as a diagnostic for short term changes in hydroxyl radical concentrations. We find no significant long-term trend in hydroxyl radical concentrations but provide evidence for recurring short-term variations of around ten per cent persisting for a few months. We also find decreases in hydroxyl radical concentrations of up to 20 per cent, apparently triggered by the eruption of Mt Pinatubo in 1991 and by the occurrence of extensive fires in Indonesia in 1997.
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Affiliation(s)
- Martin R Manning
- IPCC Working Group I Support Unit, Boulder, Colorado 80305, USA.
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21
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Jöckel P, Brenninkmeijer CAM. Natural bleach under scrutiny. Nature 2005; 436:921-2. [PMID: 16107823 DOI: 10.1038/436921a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Reimann S, Manning AJ, Simmonds PG, Cunnold DM, Wang RHJ, Li J, McCulloch A, Prinn RG, Huang J, Weiss RF, Fraser PJ, O'Doherty S, Greally BR, Stemmler K, Hill M, Folini D. Low European methyl chloroform emissions inferred from long-term atmospheric measurements. Nature 2005; 433:506-8. [PMID: 15690037 DOI: 10.1038/nature03220] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Accepted: 11/16/2004] [Indexed: 11/09/2022]
Abstract
Methyl chloroform (CH3CCl3, 1,1,1,-trichloroethane) was used widely as a solvent before it was recognized to be an ozone-depleting substance and its phase-out was introduced under the Montreal Protocol. Subsequently, its atmospheric concentration has declined steadily and recent European methyl chloroform consumption and emissions were estimated to be less than 0.1 gigagrams per year. However, data from a short-term tropospheric measurement campaign (EXPORT) indicated that European methyl chloroform emissions could have been over 20 gigagrams in 2000 (ref. 6), almost doubling previously estimated global emissions. Such enhanced emissions would significantly affect results from the CH3CC13 method of deriving global abundances of hydroxyl radicals (OH) (refs 7-12)-the dominant reactive atmospheric chemical for removing trace gases related to air pollution, ozone depletion and the greenhouse effect. Here we use long-term, high-frequency data from Mace Head, Ireland and Jungfraujoch, Switzerland, to infer European methyl chloroform emissions. We find that European emission estimates declined from about 60 gigagrams per year in the mid-1990s to 0.3-1.4 and 1.9-3.4 gigagrams per year in 2000-03, based on Mace Head and Jungfraujoch data, respectively. Our European methyl chloroform emission estimates are therefore higher than calculated from consumption data, but are considerably lower than those derived from the EXPORT campaign in 2000 (ref. 6).
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Affiliation(s)
- Stefan Reimann
- Empa, Institute of Materials Science and Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland.
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Butler TM, Rayner PJ, Simmonds I, Lawrence MG. Simultaneous mass balance inverse modeling of methane and carbon monoxide. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2005jd006071] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Yoshida Y. A three-dimensional global model study of atmospheric methyl chloride budget and distributions. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jd004951] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Dentener F. Interannual variability and trend of CH4lifetime as a measure for OH changes in the 1979–1993 time period. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jd002916] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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