226 results on '"Murray, Lee T."'
Search Results
2. Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements – corrected
- Author
-
Guo, Hao, Flynn, Clare M, Prather, Michael J, Strode, Sarah A, Steenrod, Stephen D, Emmons, Louisa, Lacey, Forrest, Lamarque, Jean-Francois, Fiore, Arlene M, Correa, Gus, Murray, Lee T, Wolfe, Glenn M, St. Clair, Jason M, Kim, Michelle, Crounse, John, Diskin, Glenn, DiGangi, Joshua, Daube, Bruce C, Commane, Roisin, McKain, Kathryn, Peischl, Jeff, Ryerson, Thomas B, Thompson, Chelsea, Hanisco, Thomas F, Blake, Donald, Blake, Nicola J, Apel, Eric C, Hornbrook, Rebecca S, Elkins, James W, Hintsa, Eric J, Moore, Fred L, and Wofsy, Steven C
- Subjects
Climate Action ,Astronomical and Space Sciences ,Atmospheric Sciences ,Meteorology & Atmospheric Sciences - Abstract
The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10s (2km) merged and gap-filled observations of the key reactive species driving the chemical budgets of O3 and CH4 (O3, CH4, CO, H2O, HCHO, H2O2, CH3OOH, C2H6, higher alkanes, alkenes, aromatics, NOx, HNO3, HNO4, peroxyacetyl nitrate, and other organic nitrates), consisting of 146494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O3 and CH4 photochemical tendencies from this modeling data stream for ATom 1. We find that 80%-90% of the total reactivity lies in the top 50% of the parcels and 25%-35% in the top 10%, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100 km) differ only slightly from the 2km ATom 10s data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find generally good agreement with the reactivity rates for O3 and CH4. Models distinctly underestimate O3 production below 2km relative to the mid-troposphere, and this can be traced to lower NOx levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-to-what-matters, set of metrics for model evaluation. This paper presents a corrected version of the paper published under the same authors and title (sans "corrected") as 10.5194/acp-21-13729-2021.
- Published
- 2023
3. Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements
- Author
-
Guo, Hao, Flynn, Clare M, Prather, Michael J, Strode, Sarah A, Steenrod, Stephen D, Emmons, Louisa, Lacey, Forrest, Lamarque, Jean-Francois, Fiore, Arlene M, Correa, Gus, Murray, Lee T, Wolfe, Glenn M, St. Clair, Jason M, Kim, Michelle, Crounse, John, Diskin, Glenn, DiGangi, Joshua, Daube, Bruce C, Commane, Roisin, McKain, Kathryn, Peischl, Jeff, Ryerson, Thomas B, Thompson, Chelsea, Hanisco, Thomas F, Blake, Donald, Blake, Nicola J, Apel, Eric C, Hornbrook, Rebecca S, Elkins, James W, Hintsa, Eric J, Moore, Fred L, and Wofsy, Steven
- Subjects
Earth Sciences ,Atmospheric Sciences ,Astronomical and Space Sciences ,Meteorology & Atmospheric Sciences ,Atmospheric sciences ,Climate change science - Abstract
The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10s (2km) merged and gap-filled observations of the key reactive species driving the chemical budgets of O3 and CH4 (O3, CH4, CO, H2O, HCHO, H2O2, CH3OOH, C2H6, higher alkanes, alkenes, aromatics, NOx, HNO3, HNO4, peroxyacetyl nitrate, other organic nitrates), consisting of 146494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O3 and CH4 photochemical tendencies from this modeling data stream for ATom 1. We find that 80%-90% of the total reactivity lies in the top 50% of the parcels and 25%-35% in the top 10%, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. In other words, accurate simulation of the least reactive 50% of the troposphere is unimportant for global budgets. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100km) differ only slightly from the 2km ATom data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find excellent agreement with the loss of O3 and CH4 but sharp disagreement with production of O3. The models sharply underestimate O3 production below 4km in both Pacific and Atlantic basins, and this can be traced to lower NOx levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-to-what-matters, set of metrics for model evaluation.
- Published
- 2021
4. Large contribution of biomass burning emissions to ozone throughout the global remote troposphere
- Author
-
Bourgeois, Ilann, Peischl, Jeff, Neuman, J. Andrew, Brown, Steven S., Thompson, Chelsea R., Aikin, Kenneth C., Allen, Hannah M., Angot, Hélène, Apel, Eric C., Baublitz, Colleen B., Brewer, Jared F., Campuzano-Jost, Pedro, Commane, Róisín, Crounse, John D., Daube, Bruce C., DiGangi, Joshua P., Diskin, Glenn S., Emmons, Louisa K., Fiore, Arlene M., Gkatzelis, Georgios I., Hills, Alan, Hornbrook, Rebecca S., Huey, L. Gregory, Jimenez, Jose L., Kim, Michelle, Lacey, Forrest, McKain, Kathryn, Murray, Lee T., Nault, Benjamin A., Parrish, David D., Ray, Eric, Sweeney, Colm, Tanner, David, Wofsy, Steven C., and Ryerson, Thomas B.
- Published
- 2021
5. Large uncertainties in global hydroxyl projections tied to fate of reactive nitrogen and carbon
- Author
-
Murray, Lee T., Fiore, Arlene M., Shindell, Drew T., Naik, Vaishali, and Horowitz, Larry W.
- Published
- 2021
6. Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments
- Author
-
Fisher, Jenny A, Atlas, Elliot L, Barletta, Barbara, Meinardi, Simone, Blake, Donald R, Thompson, Chelsea R, Ryerson, Thomas B, Peischl, Jeff, Tzompa‐Sosa, Zitely A, and Murray, Lee T
- Subjects
Life Below Water ,Atmospheric Sciences ,Physical Geography and Environmental Geoscience - Abstract
Alkyl nitrates (RONO2) are important components of tropospheric reactive nitrogen that serve as reservoirs for nitrogen oxides (NOx≡ NO + NO2). Here we implement a new simulation of atmospheric methyl, ethyl, and propyl nitrate chemistry in a global chemical transport model (GEOS-Chem). We show that the model can reproduce the spatial and seasonal variability seen in a 20-year ensemble of airborne observations. Methyl nitrate accounts for 17 Gg N globally, with maxima over the tropical Pacific and Southern Ocean. Propyl nitrate is enhanced in continental boundary layers, but its global impact (6 Gg N) is limited by a short lifetime (8 days vs. 26 days for methyl nitrate and 14 days for ethyl nitrate) that inhibits long-range transport. Ethyl nitrate has the smallest impact of the three species (4 Gg N). We find that methyl nitrate is the dominant form of reactive nitrogen (NOy) in the Southern Ocean marine boundary layer, where its addition to the model corrects a large NOy underestimate in austral winter relative to recent aircraft data. RONO2 serve as a small net NOx source to the marine troposphere, except in the northern midlatitudes where the continental outflow is enriched in precursors that promote NOx loss via RONO2 formation. Recent growth in NOx emissions from East Asia has enhanced the role of RONO2 as a source of NOx to the remote free troposphere. This relationship implies projected future NOx emissions growth across the southern hemisphere may further enhance the importance of RONO2 as a NOx reservoir.
- Published
- 2018
7. Evaluating urban methane emissions from space using TROPOMI methane and carbon monoxide observations
- Author
-
Plant, Genevieve, Kort, Eric A., Murray, Lee T., Maasakkers, Joannes D., and Aben, Ilse
- Published
- 2022
- Full Text
- View/download PDF
8. How well can global chemistry models calculate the reactivity of short-lived greenhouse gases in the remote troposphere, knowing the chemical composition
- Author
-
Prather, Michael J, Flynn, Clare M, Zhu, Xin, Steenrod, Stephen D, Strode, Sarah A, Fiore, Arlene M, Correa, Gustavo, Murray, Lee T, and Lamarque, Jean-Francois
- Subjects
Earth Sciences ,Atmospheric Sciences ,Climate Action ,Meteorology & Atmospheric Sciences ,Atmospheric sciences - Abstract
We develop a new protocol for merging in situ measurements with 3-D model simulations of atmospheric chemistry with the goal of integrating these data to identify the most reactive air parcels in terms of tropospheric production and loss of the greenhouse gases ozone and methane. Presupposing that we can accurately measure atmospheric composition, we examine whether models constrained by such measurements agree on the chemical budgets for ozone and methane. In applying our technique to a synthetic data stream of 14ĝ€880 parcels along 180°ĝ€W, we are able to isolate the performance of the photochemical modules operating within their global chemistry-climate and chemistry-transport models, removing the effects of modules controlling tracer transport, emissions, and scavenging. Differences in reactivity across models are driven only by the chemical mechanism and the diurnal cycle of photolysis rates, which are driven in turn by temperature, water vapor, solar zenith angle, clouds, and possibly aerosols and overhead ozone, which are calculated in each model. We evaluate six global models and identify their differences and similarities in simulating the chemistry through a range of innovative diagnostics. All models agree that the more highly reactive parcels dominate the chemistry (e.g., the hottest 10ĝ€% of parcels control 25-30ĝ€% of the total reactivities), but do not fully agree on which parcels comprise the top 10ĝ€%. Distinct differences in specific features occur, including the spatial regions of maximum ozone production and methane loss, as well as in the relationship between photolysis and these reactivities. Unique, possibly aberrant, features are identified for each model, providing a benchmark for photochemical module development. Among the six models tested here, three are almost indistinguishable based on the inherent variability caused by clouds, and thus we identify four, effectively distinct, chemical models. Based on this work, we suggest that water vapor differences in model simulations of past and future atmospheres may be a cause of the different evolution of tropospheric O3 and CH4, and lead to different chemistry-climate feedbacks across the models.
- Published
- 2018
9. Cloud impacts on photochemistry: building a climatology of photolysis rates from the Atmospheric Tomography mission
- Author
-
Hall, Samuel R, Ullmann, Kirk, Prather, Michael J, Flynn, Clare M, Murray, Lee T, Fiore, Arlene M, Correa, Gustavo, Strode, Sarah A, Steenrod, Stephen D, Lamarque, Jean-Francois, Guth, Jonathan, Josse, Béatrice, Flemming, Johannes, Huijnen, Vincent, Abraham, N Luke, and Archibald, Alex T
- Subjects
Earth Sciences ,Atmospheric Sciences ,Climate Action ,Astronomical and Space Sciences ,Meteorology & Atmospheric Sciences ,Atmospheric sciences ,Climate change science - Abstract
Measurements from actinic flux spectroradiometers on board the NASA DC-8 during the Atmospheric Tomography (ATom) mission provide an extensive set of statistics on how clouds alter photolysis rates (J values) throughout the remote Pacific and Atlantic Ocean basins. J values control tropospheric ozone and methane abundances, and thus clouds have been included for more than three decades in tropospheric chemistry modeling. ATom made four profiling circumnavigations of the troposphere capturing each of the seasons during 2016-2018. This work examines J values from the Pacific Ocean flights of the first deployment, but publishes the complete Atom-1 data set (29 July to 23 August 2016). We compare the observed J values (every 3s along flight track) with those calculated by nine global chemistry-climate/transport models (globally gridded, hourly, for a mid-August day). To compare these disparate data sets, we build a commensurate statistical picture of the impact of clouds on J values using the ratio of J-cloudy (standard, sometimes cloudy conditions) to J-clear (artificially cleared of clouds). The range of modeled cloud effects is inconsistently large but they fall into two distinct classes: (1) models with large cloud effects showing mostly enhanced J values aloft and or diminished at the surface and (2) models with small effects having nearly clear-sky J values much of the time. The ATom-1 measurements generally favor large cloud effects but are not precise or robust enough to point out the best cloud-modeling approach. The models here have resolutions of 50-200 km and thus reduce the occurrence of clear sky when averaging over grid cells. In situ measurements also average scattered sunlight over a mixed cloud field, but only out to scales of tens of kilometers. A primary uncertainty remains in the role of clouds in chemistry, in particular, how models average over cloud fields, and how such averages can simulate measurements.
- Published
- 2018
10. Global Atmospheric Chemistry – Which Air Matters
- Author
-
Prather, Michael J, Zhu, Xin, Flynn, Clare M, Strode, Sarah A, Rodriguez, Jose M, Steenrod, Stephen D, Liu, Junhua, Lamarque, Jean-Francois, Fiore, Arlene M, Horowitz, Larry W, Mao, Jingqiu, Murray, Lee T, Shindell, Drew T, and Wofsy, Steven C
- Abstract
Abstract. An approach for analysis and modeling of global atmospheric chemistry is developed for application to measurements that provide a tropospheric climatology of those heterogeneously distributed, reactive species that control the loss of methane and the production and loss of ozone. We identify key species (e.g., O3, NOx, HNO3, HNO4, C2H3NO5, H2O, HOOH, CH3OOH, HCHO, CO, CH4, C2H6, acetaldehyde, acetone), and presume that they can be measured simultaneously in air parcels on the scale of a few km horizontally and a few tenths vertically. Six global models have prepared such climatologies (at model resolution) for August with emphasis on the vast central Pacific and Atlantic Ocean basins. We show clear differences in model generated reactivities as well as species covariances that could readily be discriminated with an unbiased climatology. A primary tool is comparison of multi-dimensional probability densities of key species weighted by frequency of occurrence as well as by the reactivity of the parcels with respect to methane and ozone. The reactivity-weighted probabilities tell us which parcels matter in this case. Testing 100-km scale models with 2-km measurements using these tools also addresses a core question about model resolution and whether fine-scale atmospheric structures matter to the overall ozone and methane budget. A new method enabling these six global chemistry-climate models to ingest an externally-sourced climatology and then compute air parcel reactivity is demonstrated. Such an observed climatology is anticipated from the NASA Atmospheric Tomography (ATom) aircraft mission (2015–2020), measuring the key species, executing profiles over the Pacific and Atlantic Ocean basins. This work is a core part of the design of ATom.
- Published
- 2017
11. Supplementary material to "Characterization of in situ cosmogenic 14CO production, retention and loss in firn and shallow ice at Summit, Greenland"
- Author
-
Hmiel, Benjamin, primary, Petrenko, Vasilii V., additional, Buizert, Christo, additional, Smith, Andrew M., additional, Dyonisius, Michael N., additional, Place, Philip, additional, Yang, Bin, additional, Hua, Quan, additional, Beaudette, Ross, additional, Severinghaus, Jeffrey P., additional, Harth, Christina, additional, Weiss, Ray F., additional, Davidge, Lindsey, additional, Diaz, Melisa, additional, Pacicco, Matthew, additional, Menking, James A., additional, Kalk, Michael, additional, Faïn, Xavier, additional, Adolph, Alden, additional, Vimont, Isaac, additional, and Murray, Lee T., additional
- Published
- 2023
- Full Text
- View/download PDF
12. Characterization of in situ cosmogenic 14CO production, retention and loss in firn and shallow ice at Summit, Greenland
- Author
-
Hmiel, Benjamin, primary, Petrenko, Vasilii V., additional, Buizert, Christo, additional, Smith, Andrew M., additional, Dyonisius, Michael N., additional, Place, Philip, additional, Yang, Bin, additional, Hua, Quan, additional, Beaudette, Ross, additional, Severinghaus, Jeffrey P., additional, Harth, Christina, additional, Weiss, Ray F., additional, Davidge, Lindsey, additional, Diaz, Melisa, additional, Pacicco, Matthew, additional, Menking, James A., additional, Kalk, Michael, additional, Faïn, Xavier, additional, Adolph, Alden, additional, Vimont, Isaac, additional, and Murray, Lee T., additional
- Published
- 2023
- Full Text
- View/download PDF
13. An observation-based, reduced-form model for oxidation in the remote marine troposphere
- Author
-
Baublitz, Colleen B., primary, Fiore, Arlene M., additional, Ludwig, Sarah M., additional, Nicely, Julie M., additional, Wolfe, Glenn M., additional, Murray, Lee T., additional, Commane, Róisín, additional, Prather, Michael J., additional, Anderson, Daniel C., additional, Correa, Gustavo, additional, Duncan, Bryan N., additional, Follette-Cook, Melanie, additional, Westervelt, Daniel M., additional, Bourgeois, Ilann, additional, Brune, William H., additional, Bui, T. Paul, additional, DiGangi, Joshua P., additional, Diskin, Glenn S., additional, Hall, Samuel R., additional, McKain, Kathryn, additional, Miller, David O., additional, Peischl, Jeff, additional, Thames, Alexander B., additional, Thompson, Chelsea R., additional, Ullmann, Kirk, additional, and Wofsy, Steven C., additional
- Published
- 2023
- Full Text
- View/download PDF
14. Isotopic constraint on the twentieth-century increase in tropospheric ozone
- Author
-
Yeung, Laurence Y., Murray, Lee. T., Martinerie, Patricia, Witrant, Emmanuel, Hu, Huanting, Banerjee, Asmita, and Orsi, Anaïs
- Subjects
Tropospheric chemistry -- Research ,Atmospheric ozone -- Analysis -- Composition ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Tropospheric ozone (O.sub.3) is a key component of air pollution and an important anthropogenic greenhouse gas.sup.1. During the twentieth century, the proliferation of the internal combustion engine, rapid industrialization and land-use change led to a global-scale increase in O.sub.3 concentrations.sup.2,3; however, the magnitude of this increase is uncertain. Atmospheric chemistry models typically predict.sup.4-7 an increase in the tropospheric O.sub.3 burden of between 25 and 50 per cent since 1900, whereas direct measurements made in the late nineteenth century indicate that surface O.sub.3 mixing ratios increased by up to 300 per cent.sup.8-10 over that time period. However, the accuracy and diagnostic power of these measurements remains controversial.sup.2. Here we use a record of the clumped-isotope composition of molecular oxygen (.sup.18O.sup.18O in O.sub.2) trapped in polar firn and ice from 1590 to 2016 ad, as well as atmospheric chemistry model simulations, to constrain changes in tropospheric O.sub.3 concentrations. We find that during the second half of the twentieth century, the proportion of .sup.18O.sup.18O in O.sub.2 decreased by 0.03 [plus or minus] 0.02 parts per thousand (95 per cent confidence interval) below its 1590-1958 ad mean, which implies that tropospheric O.sub.3 increased by less than 40 per cent during that time. These results corroborate model predictions of global-scale increases in surface pollution and vegetative stress caused by increasing anthropogenic emissions of O.sub.3 precursors.sup.4,5,11. We also estimate that the radiative forcing of tropospheric O.sub.3 since 1850 ad is probably less than +0.4 watts per square metre, consistent with results from recent climate modelling studies.sup.12. Isotope data from polar firn and ice are used to constrain the increase in tropospheric ozone between 1850 and 2005 ad., Author(s): Laurence Y. Yeung [sup.1] , Lee. T. Murray [sup.2] , Patricia Martinerie [sup.3] , Emmanuel Witrant [sup.4] , Huanting Hu [sup.1] [sup.6] , Asmita Banerjee [sup.1] , Anaïs Orsi [...]
- Published
- 2019
- Full Text
- View/download PDF
15. Drought impacts on photosynthesis, isoprene emission and atmospheric formaldehyde in a mid-latitude forest
- Author
-
Zheng, Yiqi, Unger, Nadine, Tadić, Jovan M., Seco, Roger, Guenther, Alex B., Barkley, Michael P., Potosnak, Mark J., Murray, Lee T., Michalak, Anna M., Qiu, Xuemei, Kim, Saewung, Karl, Thomas, Gu, Lianhong, and Pallardy, Stephen G.
- Published
- 2017
- Full Text
- View/download PDF
16. Nitrate chemistry in the northeast US – Part 2: Oxygen isotopes reveal differences in particulate and gas-phase formation
- Author
-
Kim, Heejeong, primary, Walters, Wendell W., additional, Bekker, Claire, additional, Murray, Lee T., additional, and Hastings, Meredith G., additional
- Published
- 2023
- Full Text
- View/download PDF
17. Tropospheric Ozone During the Last Interglacial
- Author
-
Yan, Yuzhen, primary, Banerjee, Asmita, additional, Murray, Lee T., additional, Tie, Xin, additional, and Yeung, Laurence Y., additional
- Published
- 2022
- Full Text
- View/download PDF
18. Supplementary material to "Nitrate Chemistry in the Northeast US Part II: Oxygen Isotopes Reveal Differences in Particulate and Gas Phase Formation"
- Author
-
Kim, Heejeong, primary, Walters, Wendell W., additional, Bekker, Claire, additional, Murray, Lee T., additional, and Hastings, Meredith G., additional
- Published
- 2022
- Full Text
- View/download PDF
19. Nitrate Chemistry in the Northeast US Part II: Oxygen Isotopes Reveal Differences in Particulate and Gas Phase Formation
- Author
-
Kim, Heejeong, primary, Walters, Wendell W., additional, Bekker, Claire, additional, Murray, Lee T., additional, and Hastings, Meredith G., additional
- Published
- 2022
- Full Text
- View/download PDF
20. Supplementary material to "Nitrate chemistry in the northeast US part I: nitrogen isotope seasonality tracks nitrate formation chemistry"
- Author
-
Bekker, Claire, primary, Walters, Wendell W., additional, Murray, Lee T., additional, and Hastings, Meredith G., additional
- Published
- 2022
- Full Text
- View/download PDF
21. Nitrate chemistry in the northeast US part I: nitrogen isotope seasonality tracks nitrate formation chemistry
- Author
-
Bekker, Claire, primary, Walters, Wendell W., additional, Murray, Lee T., additional, and Hastings, Meredith G., additional
- Published
- 2022
- Full Text
- View/download PDF
22. Supplementary material to "Intercomparison of commercial analyzers for atmospheric ethane and methane observations"
- Author
-
Commane, Roisin, primary, Hallward-Driemeier, Andrew, additional, and Murray, Lee T., additional
- Published
- 2022
- Full Text
- View/download PDF
23. Intercomparison of commercial analyzers for atmospheric ethane and methane observations
- Author
-
Commane, Roisin, primary, Hallward-Driemeier, Andrew, additional, and Murray, Lee T., additional
- Published
- 2022
- Full Text
- View/download PDF
24. Supplementary material to "Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements"
- Author
-
Guo, Hao, primary, Flynn, Clare M., additional, Prather, Michael J., additional, Strode, Sarah A., additional, Steenrod, Stephen D., additional, Emmons, Louisa, additional, Lacey, Forrest, additional, Lamarque, Jean-Francois, additional, Fiore, Arlene M., additional, Correa, Gus, additional, Murray, Lee T., additional, Wolfe, Glenn M., additional, St. Clair, Jason M., additional, Kim, Michelle, additional, Crounse, John, additional, Diskin, Glenn, additional, DiGangi, Joshua, additional, Daube, Bruce C., additional, Commane, Roisin, additional, McKain, Kathryn, additional, Peischl, Jeff, additional, Ryerson, Thomas B., additional, Thompson, Chelsea, additional, Hanisco, Thomas F., additional, Blake, Donald, additional, Blake, Nicola J., additional, Apel, Eric C., additional, Hornbrook, Rebecca S., additional, Elkins, James W., additional, Hintsa, Eric J., additional, Moore, Fred L., additional, and Wofsy, Steven C., additional
- Published
- 2022
- Full Text
- View/download PDF
25. Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements
- Author
-
Guo, Hao, primary, Flynn, Clare M., additional, Prather, Michael J., additional, Strode, Sarah A., additional, Steenrod, Stephen D., additional, Emmons, Louisa, additional, Lacey, Forrest, additional, Lamarque, Jean-Francois, additional, Fiore, Arlene M., additional, Correa, Gus, additional, Murray, Lee T., additional, Wolfe, Glenn M., additional, St. Clair, Jason M., additional, Kim, Michelle, additional, Crounse, John, additional, Diskin, Glenn, additional, DiGangi, Joshua, additional, Daube, Bruce C., additional, Commane, Roisin, additional, McKain, Kathryn, additional, Peischl, Jeff, additional, Ryerson, Thomas B., additional, Thompson, Chelsea, additional, Hanisco, Thomas F., additional, Blake, Donald, additional, Blake, Nicola J., additional, Apel, Eric C., additional, Hornbrook, Rebecca S., additional, Elkins, James W., additional, Hintsa, Eric J., additional, Moore, Fred L., additional, and Wofsy, Steven C., additional
- Published
- 2022
- Full Text
- View/download PDF
26. Nitrogen Oxides in the Global Upper Troposphere: Interpreting Cloud-Sliced NO2 Observations from the OMI Satellite Instrument
- Author
-
Marais, Eloise A, Jacob, Daniel J, Choi, Sungyeon, Joiner, Joanna, Belmonte-Rivas, Maria, Cohen, Ronald C, Beirle, Steffen, Murray, Lee T, Schiferl, Luke D, Shah, Viral, and Jaegle, Lyatt
- Subjects
Earth Resources And Remote Sensing - Abstract
Nitrogen oxides (NOx≡NO+NO2) in the upper troposphere (UT) have a large impact on global tropospheric ozone and OH (the main atmospheric oxidant). New cloud-sliced observations of UT NO2 at 450–280 hPa (∼6–9 km) from the Ozone Monitoring Instrument (OMI) produced by NASA and the Royal Netherlands Meteorological Institute (KNMI) provide global coverage to test our understanding of the factors controlling UT NOx. We find that these products offer useful information when averaged over coarse scales (20°×32°, seasonal), and that the NASA product is more consistent with aircraft observations of UT NO2. Correlation with Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) satellite observations of lightning flash frequencies suggests that lightning is the dominant source of NOx to the upper troposphere except for extratropical latitudes in winter. The NO2 background in the absence of lightning is 10–20 pptv. We infer a global mean NOx yield of 280±80 moles per lightning flash, with no significant difference between the tropics and midlatitudes, and a global lightning NOx source of 5.9±1.7 Tg N a(exp −1). There is indication that the NOx yield per flash increases with lightning flash footprint and with flash energy.
- Published
- 2018
- Full Text
- View/download PDF
27. Attribution of Stratospheric and Tropospheric Ozone Changes Between 1850 and 2014 in CMIP6 Models
- Author
-
Zeng, Guang, primary, Morgenstern, Olaf, additional, Williams, Jonny H. T., additional, O’Connor, Fiona M., additional, Griffiths, Paul T., additional, Keeble, James, additional, Deushi, Makoto, additional, Horowitz, Larry W., additional, Naik, Vaishali, additional, Emmons, Louisa K., additional, Abraham, N. Luke, additional, Archibald, Alexander T., additional, Bauer, Susanne E., additional, Hassler, Birgit, additional, Michou, Martine, additional, Mills, Michael J., additional, Murray, Lee T., additional, Oshima, Naga, additional, Sentman, Lori T., additional, Tilmes, Simone, additional, Tsigaridis, Kostas, additional, and Young, Paul J., additional
- Published
- 2022
- Full Text
- View/download PDF
28. Hydrogen Sulfide Emission Properties from Two Large Landfills in New York State
- Author
-
Catena, Alexandra M., primary, Zhang, Jie, additional, Commane, Roisin, additional, Murray, Lee T., additional, Schwab, Margaret J., additional, Leibensperger, Eric M., additional, Marto, Joseph, additional, Smith, Mackenzie L., additional, and Schwab, James J., additional
- Published
- 2022
- Full Text
- View/download PDF
29. Clumped‐Isotope Constraint on Upper‐Tropospheric Cooling During the Last Glacial Maximum
- Author
-
Banerjee, Asmita, primary, Yeung, Laurence Y., additional, Murray, Lee T., additional, Tie, Xin, additional, Tierney, Jessica E., additional, and Legrande, Allegra N., additional
- Published
- 2022
- Full Text
- View/download PDF
30. Future Climate Change Under SSP Emission Scenarios With GISS‐E2.1
- Author
-
Nazarenko, Larissa S., primary, Tausnev, Nick, additional, Russell, Gary L., additional, Rind, David, additional, Miller, Ron L., additional, Schmidt, Gavin A., additional, Bauer, Susanne E., additional, Kelley, Maxwell, additional, Ruedy, Reto, additional, Ackerman, Andrew S., additional, Aleinov, Igor, additional, Bauer, Michael, additional, Bleck, Rainer, additional, Canuto, Vittorio, additional, Cesana, Grégory, additional, Cheng, Ye, additional, Clune, Thomas L., additional, Cook, Ben I., additional, Cruz, Carlos A., additional, Del Genio, Anthony D., additional, Elsaesser, Gregory S., additional, Faluvegi, Greg, additional, Kiang, Nancy Y., additional, Kim, Daehyun, additional, Lacis, Andrew A., additional, Leboissetier, Anthony, additional, LeGrande, Allegra N., additional, Lo, Ken K., additional, Marshall, John, additional, Matthews, Elaine E., additional, McDermid, Sonali, additional, Mezuman, Keren, additional, Murray, Lee T., additional, Oinas, Valdar, additional, Orbe, Clara, additional, García‐Pando, Carlos Pérez, additional, Perlwitz, Jan P., additional, Puma, Michael J., additional, Romanou, Anastasia, additional, Shindell, Drew T., additional, Sun, Shan, additional, Tsigaridis, Kostas, additional, Tselioudis, George, additional, Weng, Ensheng, additional, Wu, Jingbo, additional, and Yao, Mao‐Sung, additional
- Published
- 2022
- Full Text
- View/download PDF
31. Investigating the sensitivity of surface-level nitrate seasonality in Antarctica to primary sources using a global model
- Author
-
Lee, Hyung-Min, Henze, Daven K., Alexander, Becky, and Murray, Lee T.
- Published
- 2014
- Full Text
- View/download PDF
32. Nitrate chemistry in the northeast US – Part 1: Nitrogen isotope seasonality tracks nitrate formation chemistry.
- Author
-
Bekker, Claire, Walters, Wendell W., Murray, Lee T., and Hastings, Meredith G.
- Subjects
ATMOSPHERIC nitrogen ,NITROGEN isotopes ,PARTICULATE nitrate ,CARBONACEOUS aerosols ,NITRATES ,STABLE isotope analysis ,ATMOSPHERIC deposition - Abstract
Despite significant precursor emission reductions in the US over recent decades, atmospheric nitrate deposition remains an important terrestrial stressor. Here, we utilized statistical air mass back trajectory analysis and nitrogen stable isotope deltas (δ (15 N)) to investigate atmospheric nitrate spatiotemporal trends in the northeastern US from samples collected at three US EPA Clean Air Status and Trends Network (CASTNET) sites from December 2016–2018. For the considered sites, similar seasonal patterns in nitric acid (HNO 3) and particulate nitrate (pNO 3) concentrations were observed with spatial differences attributed to nitrogen oxide (NO x) emission densities in source contributing regions that were typically ≤ 1000 km. Significant spatiotemporal δ (15 N) variabilities in HNO 3 and pNO 3 were observed with higher values during winter relative to summer, like previous reports from CASTNET samples collected in the early 2000s for our study region. In the early 2000s, δ (15 N) of atmospheric nitrate in the northeast US had been suggested to be driven by NO x emissions; however, we did not find significant spatiotemporal changes in the modeled NO x emissions by sector and fuel type or δ (15 N, NO x) for the source regions of the CASTNET sites. Instead, the seasonal and spatial differences in the observed δ (15 N) of atmospheric nitrate were driven by nitrate formation pathways (i.e., homogeneous reactions of NO 2 oxidation via hydroxyl radical or heterogeneous reactions of dinitrogen pentoxide on wetted aerosol surfaces) and their associated δ (15 N) fractionation. Under the field conditions of low NO x relative to O 3 concentrations and when δ (15 N, NO x) emission sources do not have significant variability, we demonstrate that δ (15 N) of atmospheric nitrate can be a robust tracer for diagnosing nitrate formation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. Intercomparison of commercial analyzers for atmospheric ethane and methane observations.
- Author
-
Commane, Róisín, Hallward-Driemeier, Andrew, and Murray, Lee T.
- Subjects
ATMOSPHERIC methane ,ETHANES ,NATURAL gas ,CLIMATE change mitigation ,MOBILE operating systems ,METHANE ,WATER vapor ,CARBONACEOUS aerosols - Abstract
Methane (CH 4) is a strong greenhouse gas that has become the focus of climate mitigation policies in recent years. Ethane/methane ratios can be used to identify and partition the different sources of methane, especially in areas with natural gas mixed with biogenic methane emissions, such as cities. We assessed the precision, accuracy, and selectivity of three commercially available laser-based analyzers that have been marketed as measuring instantaneous dry-mole fractions of methane and ethane in ambient air. The Aerodyne SuperDUAL instrument performed the best out of the three instruments, but it is large and requires expertise to operate. The Aeris Mira Ultra LDS analyzer also performed well for the price point and small size, but it required characterization of the water vapor dependence of reported concentrations and careful set-up for use. The Picarro G2210-i precisely measured methane, but it did not detect the 10 ppbv (part-per-billion by volume) increases in ambient ethane detected by the other two instruments when sampling a plume of incompletely combusted natural gas. For long-term tower deployments or those with large mobile laboratories, the Aerodyne SuperDUAL provides the best precision for methane and ethane. The more compact Aeris MIRA can, with careful use, quantify thermogenic methane sources to sufficient precision for mobile and short-term deployments in urban or oil and gas areas. We weighed the advantages of each instrument, including size, power requirement, ease of use on mobile platforms, and expertise needed to operate the instrument. We recommend the Aerodyne SuperDUAL or the Aeris MIRA Ultra LDS depending on the situation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. Average Versus High Surface Ozone Levels over the Continental USA: Model Bias, Background Influences, and Interannual Variability
- Author
-
Guo, Jean J, Fiore, Arlene M, Murray, Lee T, Jaffe, Daniel A, Schnell, Jordan L, Moore, Charles T, and Milly, George P
- Subjects
Meteorology And Climatology - Abstract
US background ozone (O3) includes O3 produced from anthropogenic O3 precursors emitted outside of the USA, from global methane, and from any natural sources. Using a suite of sensitivity simulations in the GEOS-Chem global chemistry transport model, we estimate the influence from individual background sources versus US anthropogenic sources on total surface O3 over 10 continental US regions from 2004 to 2012. Evaluation with observations reveals model biases of +0-19ppb in seasonal mean maximum daily 8h average (MDA8) O3, highest in summer over the eastern USA. Simulated high-O3 events cluster too late in the season. We link these model biases to excessive regional O3 production (e.g., US anthropogenic, biogenic volatile organic compounds (BVOCs), and soil NOx, emissions), or coincident missing sinks. On the 10 highest observed O3 days during summer (O3_top10obs_JJA), US anthropogenic emissions enhance O3 by 5-11ppb and by less than 2ppb in the eastern versus western USA. The O3 enhancement from BVOC emissions during summer is 1-7 ppb higher on O3_top10obs_JJA days than on average days, while intercontinental pollution is up to 2ppb higher on average versus on O3_top10obs_JJA days. During the summers of 2004-2012, monthly regional mean US background O3 MDA8 levels vary by up to 15ppb from year to year. Observed and simulated summertime total surface O3 levels on O3_top10obs_JJA days decline by 3ppb (averaged over all regions) from 2004-2006 to 2010-2012, reflecting rising US background (+2ppb) and declining US anthropogenic O3 emissions (6ppb) in the model. The model attributes interannual variability in US background O3 on O3_top10obs days to natural sources, not international pollution transport. We find that a 3-year averaging period is not long enough to eliminate interannual variability in background O3 on the highest observed O3 days.
- Published
- 2018
- Full Text
- View/download PDF
35. Chemical Modeling of the Reactivity of Short-Lived Greenhouse Gases: A Model Inter-Comparison Prescribing a Well-Measured, Remote Troposphere
- Author
-
Prather, Michael J, Flynn, Clare M, Zhu, Xin, Steenrod, Stephen D, Strode, Sarah A, Fiore, Arlene M, Correa, Gustavo, Murray, Lee T, and Lamarque, Jean-Francois
- Subjects
Computer Programming And Software ,Environment Pollution - Abstract
We develop a new protocol for merging in situ measurements with 3-D model simulations of atmospheric chemistry with the goal of integrating over the data to identify the most reactive air parcels in terms of tropospheric production and loss of the greenhouse gases ozone and methane. Presupposing that we can accurately measure atmospheric composition, we examine whether models constrained by such measurements agree on the chemical budgets for ozone and methane. In applying our technique to a synthetic data stream of 14,880 parcels along 180W, we are able to isolate the performance of the photochemical modules operating within their global chemistry-climate and chemistry-transport models, removing the effects of modules controlling tracer transport, emissions, and scavenging. Differences in reactivity across models are driven only by the chemical mechanism and the diurnal cycle of photolysis rates, which are driven in turn by temperature, water vapor, solar zenith angle, clouds, and possibly aerosols and overhead ozone, which are calculated in each model. We evaluate six global models and identify their differences and similarities in simulating the chemistry through a range of innovative diagnostics. All models agree that the more highly reactive parcels dominate the chemistry (e.g., the hottest 10% of parcels control 25-30% of the total reactivities), but do not fully agree on which parcels comprise the top 10%. Distinct differences in specific features occur, including the regions of maximum ozone production and methane loss, as well as in the relationship between photolysis and these reactivities. Unique, possibly aberrant, features are identified for each model, providing a benchmark for photochemical module development. Among the 6 models tested here, 3 are almost indistinguishable based on the inherent variability caused by clouds, and thus we identify 4, effectively distinct, chemical models. Based on this work, we suggest that water vapor differences in model simulations of past and future atmospheres may be a cause of the different evolution of tropospheric O3 and CH4, and lead to different chemistry-climate feedbacks across the models.
- Published
- 2018
- Full Text
- View/download PDF
36. Lightning NO x and Impacts on Air Quality
- Author
-
Murray, Lee T.
- Published
- 2016
- Full Text
- View/download PDF
37. The NASA Atmospheric Tomography (ATom) Mission: Imaging the Chemistry of the Global Atmosphere
- Author
-
Thompson, Chelsea R., primary, Wofsy, Steven C., additional, Prather, Michael J., additional, Newman, Paul A., additional, Hanisco, Thomas F., additional, Ryerson, Thomas B., additional, Fahey, David W., additional, Apel, Eric C., additional, Brock, Charles A., additional, Brune, William H., additional, Froyd, Karl, additional, Katich, Joseph M., additional, Nicely, Julie M., additional, Peischl, Jeff, additional, Ray, Eric, additional, Veres, Patrick R., additional, Wang, Siyuan, additional, Allen, Hannah M., additional, Asher, Elizabeth, additional, Bian, Huisheng, additional, Blake, Donald, additional, Bourgeois, Ilann, additional, Budney, John, additional, Bui, T. Paul, additional, Butler, Amy, additional, Campuzano-Jost, Pedro, additional, Chang, Cecilia, additional, Chin, Mian, additional, Commane, Róisín, additional, Correa, Gus, additional, Crounse, John D., additional, Daube, Bruce, additional, Dibb, Jack E., additional, DiGangi, Joshua P., additional, Diskin, Glenn S., additional, Dollner, Maximilian, additional, Elkins, James W., additional, Fiore, Arlene M., additional, Flynn, Clare M., additional, Guo, Hao, additional, Hall, Samuel R., additional, Hannun, Reem A., additional, Hills, Alan, additional, Hintsa, Eric J., additional, Hodzic, Alma, additional, Hornbrook, Rebecca S., additional, Huey, L. Greg, additional, Jimenez, Jose L., additional, Keeling, Ralph F., additional, Kim, Michelle J., additional, Kupc, Agnieszka, additional, Lacey, Forrest, additional, Lait, Leslie R., additional, Lamarque, Jean-Francois, additional, Liu, Junhua, additional, McKain, Kathryn, additional, Meinardi, Simone, additional, Miller, David O., additional, Montzka, Stephen A., additional, Moore, Fred L., additional, Morgan, Eric J., additional, Murphy, Daniel M., additional, Murray, Lee T., additional, Nault, Benjamin A., additional, Neuman, J. Andrew, additional, Nguyen, Louis, additional, Gonzalez, Yenny, additional, Rollins, Andrew, additional, Rosenlof, Karen, additional, Sargent, Maryann, additional, Schill, Gregory, additional, Schwarz, Joshua P., additional, Clair, Jason M. St., additional, Steenrod, Stephen D., additional, Stephens, Britton B., additional, Strahan, Susan E., additional, Strode, Sarah A., additional, Sweeney, Colm, additional, Thames, Alexander B., additional, Ullmann, Kirk, additional, Wagner, Nicholas, additional, Weber, Rodney, additional, Weinzierl, Bernadett, additional, Wennberg, Paul O., additional, Williamson, Christina J., additional, Wolfe, Glenn M., additional, and Zeng, Linghan, additional
- Published
- 2022
- Full Text
- View/download PDF
38. Isotopic Ordering in Atmospheric O2 as a Tracer of Ozone Photochemistry and the Tropical Atmosphere
- Author
-
Yeung, Laurence Y, Murray, Lee T, Ash, Jeanine L, Young, Edward D, Boering, Kristie A, Atlas, Elliot L, Schauffler, Sue M, Lueb, Richard A, Langenfelds, Ray L, Krummel, Paul B, Steele, L. Paul, and Eastham, Sebastian D
- Subjects
Meteorology And Climatology ,Geophysics - Abstract
The distribution of isotopes within O2 molecules can be rapidly altered when they react with atomic oxygen. This mechanism is globally important: while other contributions to the global budget of O2 impart isotopic signatures, the O(3P) + O2 reaction resets all such signatures in the atmosphere on subdecadal timescales. Consequently, the isotopic distribution within O2 is determined by O3 photochemistry and the circulation patterns that control where that photochemistry occurs. The variability of isotopic ordering in O2 has not been established, however. We present new measurements of 18O18O in air (reported as delta36 values) from the surface to 33 km altitude. They confirm the basic features of the clumped-isotope budget of O2: Stratospheric air has higher delta36 values than tropospheric air (i.e., more 18O18O), reflecting colder temperatures and fast photochemical cycling of O3. Lower delta36 values in the troposphere arise from photochemistry at warmer temperatures balanced by the influx of high-delta36 air from the stratosphere. These observations agree with predictions derived from the GEOS-Chem chemical transport model, which provides additional insight. We find a link between tropical circulation patterns and regions where delta36 values are reset in the troposphere. The dynamics of these regions influences lapse rates, vertical and horizontal patterns of O2 reordering, and thus the isotopic distribution toward which O2 is driven in the troposphere. Temporal variations in delta36 values at the surface should therefore reflect changes in tropospheric temperatures, photochemistry, and circulation. Our results suggest that the tropospheric O3 burden has remained within a +/-10 percent range since 1978.
- Published
- 2016
- Full Text
- View/download PDF
39. An uncertain future for lightning
- Author
-
Murray, Lee T.
- Published
- 2018
- Full Text
- View/download PDF
40. Grid-stretching capability for the GEOS-Chem 13.0.0 atmospheric chemistry model
- Author
-
Bindle, Liam, primary, Martin, Randall V., additional, Cooper, Matthew J., additional, Lundgren, Elizabeth W., additional, Eastham, Sebastian D., additional, Auer, Benjamin M., additional, Clune, Thomas L., additional, Weng, Hongjian, additional, Lin, Jintai, additional, Murray, Lee T., additional, Meng, Jun, additional, Keller, Christoph A., additional, Putman, William M., additional, Pawson, Steven, additional, and Jacob, Daniel J., additional
- Published
- 2021
- Full Text
- View/download PDF
41. GCAP 2.0: a global 3-D chemical-transport model framework for past, present, and future climate scenarios
- Author
-
Murray, Lee T., primary, Leibensperger, Eric M., additional, Orbe, Clara, additional, Mickley, Loretta J., additional, and Sulprizio, Melissa, additional
- Published
- 2021
- Full Text
- View/download PDF
42. Anthropogenic Impacts on Tropospheric Reactive Chlorine Since the Preindustrial
- Author
-
Zhai, Shuting, Wang, Xuan, McConnell, Joseph R., Geng, Lei, Cole-Dai, Jihong, Sigl, Michael, Chellman, Nathan, Sherwen, Tomás, Pound, Ryan, Fujita, Koji, Hattori, Shohei, Moch, Jonathan M., Zhu, Lei, Evans, Mat, Legrand, Michel, Liu, Pengfei, Pasteris, Daniel, Chan, Yuk Chun, Murray, Lee T., and Alexander, Becky
- Subjects
body regions ,530 Physics ,540 Chemistry - Abstract
Tropospheric reactive gaseous chlorine (Cly) impacts the atmosphere���s oxidation capacity with implications for chemically reduced gases such as methane. Here we use Greenland ice-core records of chlorine, sodium, and acidity, and global model simulations to show how tropospheric Cly has been impacted by anthropogenic emissions since the 1940s. We show that anthropogenic contribution of non-sea-salt chlorine significantly influenced total chlorine and its trends after the 1940s. The modeled regional 170% Cly increase from preindustrial to the 1970s was driven by acid displacement from sea-salt-aerosol, direct emission of hydrochloric acid (HCl) from combustion, and chemical reactions driven by anthropogenic nitrogen oxide (NOx) emissions. Since the 1970s, the modeled 6% Cly decrease was caused mainly by reduced anthropogenic HCl emissions from air pollution mitigation policies. Our findings suggest that anthropogenic emissions of acidic gases and their emission control strategies have substantial impacts on Cly with implications for tropospheric oxidants, methane, and mercury.
- Published
- 2021
43. Nitrate Chemistry in the Northeast US Part II: Oxygen Isotopes Reveal Differences in Particulate and Gas Phase Formation.
- Author
-
Heejeong Kim, Walters, Wendell W., Bekker, Claire, Murray, Lee T., and Hastings, Meredith G.
- Abstract
The northeastern US represents a mostly urban corridor impacted by high population density, high emissions density and degraded air quality and acid rain that has been a focus of regulatory-driven emissions reductions. Detailing the chemistry of atmospheric nitrate formation is critical for improving model representation of atmospheric chemistry and air quality. The oxygen isotope deltas (δ(
18 O) and Δ(17 O)) of atmospheric nitrate are useful indicators in tracking nitrate formation pathways. Here, we measured Δ(17 O) and δ(18 O) for nitric acid (HNO3 ) and particulate nitrate (pNO3 ) from three US EPA Clean Air Status and Trends Network (CASTNET) sites in the northeastern US from December 2016 to 2018. The Δ(17 O, HNO3 ) and δ(18 O, HNO3 ) values ranged from 12.9 ‰ to 30.9 ‰ and from 46.9 ‰ to 82.1 ‰, and the Δ(17 O, pNO3 ) and δ(18 O, pNO) ranged from 16.6 ‰ to 33.7 ‰ and from 43.6 ‰ to 85.3 ‰, respectively. There was distinct seasonality of δ(18 O) and Δ(17 O) with higher values observed during winter compared to summer, suggesting a shift in O3 to HOx radical chemistry, as expected. Unexpectedly, there was a statistical difference in Δ(17 O) between HNO3 and pNO3 , with higher values observed for pNO3 (27.1±3.8) ‰ relative to HNO3 (22.7±3.6) ‰, and significant differences in the relationship between δ(18 O) and Δ(17 O). This difference suggests atmospheric nitrate phase-dependent 29 oxidation chemistry that is not predicted in models. Based on output from GEOS-Chem, and both the δ(18 O) and Δ(17 O) observations, we quantify the production pathways of atmospheric nitrate. The model significantly overestimated the heterogeneous N2 O5 hydrolysis production for both HNO3 and pNO3 , a finding consistent with observed seasonal changes in δ(18 O), Δ(17 O) and δ(15 N) of HNO3 and pNO3 , though large uncertainties remain in the quantitative transfer of δ(18 O) from major atmospheric oxidants. This comparison provides important insight into the role of oxidation chemistry in reconciling a commonly observed positive bias for model atmospheric nitrate concentrations in the northeastern US. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
44. Nitrate chemistry in the northeast US part I: nitrogen isotope seasonality tracks nitrate formation chemistry.
- Author
-
Bekker, Claire, Walters, Wendell W., Murray, Lee T., and Hastings, Meredith G.
- Abstract
Despite significant precursor emission reductions in the US over recent decades, atmospheric nitrate deposition remains an important terrestrial stressor. Here we utilized statistical air mass back trajectory analysis and nitrogen stable isotope deltas (δ(
15 N)) to investigate atmospheric nitrate spatiotemporal trends in the northeastern US from samples collected at three US EPA Clean Air Status and Trends Network (CASTNET) sites from December 2016–2018. For the considered sites, similar seasonal patterns in nitric acid (HNO3 ) and particulate nitrate (p NO3 ) concentrations were observed with spatial differences attributed to nitrogen oxide (NOx ) emission densities in source contributing regions that were typically ≤1000 km. Significant spatiotemporal δ(15 N) variabilities in HNO3 andp NO3 were observed with higher values during winter relative to summer, like previous reports from CASTNET samples collected in the early 2000s for our study region. In the early 2000s, δ(15 N) of atmospheric nitrate in the Northeast US had been suggested to be driven by NOx emissions; however, we did not find significant spatiotemporal changes in the modeled NOx emissions by sector and fuel type or δ(15 N, NOx ) for the source regions of the CASTNET sites. Instead, the spatiotemporal trends were driven by δ(15 N) fractionation associated with nitrate formation. Under the field conditions of low NOx relative to O3 concentrations and when δ(15 N, NOx ) emission sources do not have significant variability, we demonstrate that δ(15 N) of atmospheric nitrate can be a robust tracer for diagnosing nitrate formation. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
45. Intercomparison of commercial analyzers for atmospheric ethane and methane observations.
- Author
-
Commane, Róisín, Hallward-Driemeier, Andrew, and Murray, Lee T.
- Subjects
ATMOSPHERIC methane ,NATURAL gas ,ETHANES ,MOBILE operating systems ,CLIMATE change mitigation ,MOLE fraction ,METHANE ,CARBONACEOUS aerosols - Abstract
Methane (CH4) is a strong greenhouse gas that has become the focus of climate mitigation policies in recent years. Ethane/methane ratios can be used to identify and partition the difference sources of methane, especially in areas with natural gas mixed with biogenic methane emissions, such as cities. We assessed the precision, accuracy and selectivity of three commercially available laser-based analyzers that have been marketed as measuring instantaneous dry mole fractions of methane and ethane in ambient air. The Aerodyne SuperDUAL instrument performed best of the three instruments but it requires expertise to operate and space for the large footprint. The Aeris Mira Ultra LDS analyzer also performed well for the price point and small footprint but required characterization of the water vapor dependence of reported concentrations and careful setup for use. The Picarro G2210-i precisely measured methane but it did not detect the 10 ppbv increases in ambient ethane detected by the other two instruments when sampling a plume of incompletely combusted natural gas. For long-term tower deployments or those with large mobile laboratories, the Aerodyne SuperDUAL provides the best precision for methane and ethane. For smaller mobile platforms, the Aeris MIRA is a more compact analyzer, and with careful use, can quantify thermogenic methane sources to sufficient precision for short term deployments in urban or oil and gas areas. We weighed the advantages of each instrument, including size, power requirement, ease of use on mobile platforms, and expertise needed to operate the instrument, and we recommend the Aerodyne SuperDUAL or the Aeris MIRA Ultra LDS depending on the situation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. Tropospheric ozone in CMIP6 Simulations
- Author
-
Griffiths, Paul T, Murray, Lee T, Zeng, Guang, Archibald, Alexander T, Emmons, Louisa K, Galbally, Ian, Hassler, Birgit, Horowitz, Larry W, Keeble, James, Liu, Jane, Moeini, Omid, Naik, Vaishali, O'Connor, Fiona M, Shin, Youngsub Matthew, Tarasick, David, Tilmes, Simone, Turnock, Steven T, Wild, Oliver, Young, Paul J, Zanis, Prodromos, Griffiths, Paul T [0000-0002-1089-340X], Murray, Lee T [0000-0002-3447-3952], Zeng, Guang [0000-0002-9356-5021], Archibald, Alexander T [0000-0001-9302-4180], Emmons, Louisa K [0000-0003-2325-6212], Galbally, Ian [0000-0003-2383-1360], Hassler, Birgit [0000-0003-2724-709X], Liu, Jane [0000-0001-7760-2788], Tilmes, Simone [0000-0002-6557-3569], Turnock, Steven T [0000-0002-0036-4627], Wild, Oliver [0000-0002-6227-7035], Young, Paul J [0000-0002-5608-8887], and Apollo - University of Cambridge Repository
- Subjects
13 Climate Action ,3701 Atmospheric Sciences ,37 Earth Sciences - Abstract
The evolution of tropospheric ozone from 1850 to 2100 has been studied using data from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). We evaluate long-term changes using coupled atmosphere-ocean chemistry-climate models, focusing on the CMIP historical and ScenarioMIP ssp370 experiments, for which detailed tropospheric ozone diagnostics were archived. The model ensemble has been evaluated against a suite of surface, sonde, and satellite observations of the past several decades, and found to reproduce well the salient spatial, seasonal and decadal variability and trends. The tropospheric ozone burden increases from 244 ± 30 Tg in 1850 to a mean value of 348 ± 15 Tg for the period 2005–2014, an increase of 40 %. Modelled present day values agree well with previous determinations (ACCENT: 336 ± 27 Tg; ACCMIP: 337 ± 23 Tg and TOAR: 340 ± 34 Tg). In the ssp370 experiments, the ozone burden reaches a maximum of 402 ± 36 Tg in 2090, before declining slightly to 396 ± 32 Tg by 2100. The ozone budget has been examined over the same period using lumped ozone production (PO3) and loss (LO3) diagnostics. There are large differences (30 %) between models in the preindustrial period, with the difference narrowing to 15 % in the present day. Both ozone production and chemical loss terms increase steadily over the period 1850 to 2100, with net chemical production (PO3-LO3) reaching a maximum around the year 2000. The residual term, which contains contributions from stratosphere-troposphere transport reaches a minimum around the same time, while dry deposition increases steadily across the experiment. Differences between the model residual terms are explained in terms of variation in tropopause height and stratospheric ozone burden.
- Published
- 2020
47. Evaluation of UTLS Carbon Monoxide Simulations in GMI and GEOS-Chem Chemical Transport Models using Aura MLS Observations
- Author
-
Huang, Lei, Jiang, Jonathan H, Murray, Lee T, Damon, Megan R, Su, Hui, and Livesey, Nathaniel J
- Subjects
Meteorology And Climatology - Abstract
This study evaluates the distribution and variation of carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) during 2004-2012 as simulated by two chemical transport models, using the latest version of Aura Microwave Limb Sounder (MLS) observations. The simulated spatial distributions, temporal variations and vertical transport of CO in the UTLS region are compared with those observed by MLS. We also investigate the impact of surface emissions and deep convection on CO concentrations in the UTLS over different regions, using both model simulations and MLS observations. Global Modeling Initiative (GMI) and GEOS-Chem simulations of UTLS CO both show similar spatial distributions to observations. The global mean CO values simulated by both models agree with MLS observations at 215 and 147 hPa, but are significantly underestimated by more than 40% at 100 hPa. In addition, the models underestimate the peak CO values by up to 70% at 100 hPa, 60% at 147 hPa and 40% at 215 hPa, with GEOS-Chem generally simulating more CO at 100 hPa and less CO at 215 hPa than GMI. The seasonal distributions of CO simulated by both models are in better agreement with MLS in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), with disagreements between model and observations over enhanced CO regions such as southern Africa. The simulated vertical transport of CO shows better agreement with MLS in the tropics and the SH subtropics than the NH subtropics. We also examine regional variations in the relationships among surface CO emission, convection and UTLS CO concentrations. The two models exhibit emission-convection- CO relationships similar to those observed by MLS over the tropics and some regions with enhanced UTLS CO.
- Published
- 2016
- Full Text
- View/download PDF
48. Effects of Ozone Isotopologue Formation on the Clumped‐Isotope Composition of Atmospheric O 2
- Author
-
Yeung, Laurence Y., primary, Murray, Lee T., additional, Banerjee, Asmita, additional, Tie, Xin, additional, Yan, Yuzhen, additional, Atlas, Elliot L., additional, Schauffler, Sue M., additional, and Boering, Kristie A., additional
- Published
- 2021
- Full Text
- View/download PDF
49. Supplementary material to "Heterogeneity and Chemical Reactivity of the Remote Troposphere defined by Aircraft Measurements"
- Author
-
Guo, Hao, primary, Flynn, Clare M., additional, Prather, Michael J., additional, Strode, Sarah A., additional, Steenrod, Stephen D., additional, Emmons, Louisa, additional, Lacey, Forrest, additional, Lamarque, Jean-Francois, additional, Fiore, Arlene M., additional, Correa, Gus, additional, Murray, Lee T., additional, Wolfe, Glenn M., additional, St. Clair, Jason M., additional, Kim, Michelle, additional, Crounse, John, additional, Diskin, Glenn, additional, DiGangi, Joshua, additional, Daube, Bruce C., additional, Commane, Roisin, additional, McKain, Kathryn, additional, Peischl, Jeff, additional, Ryerson, Thomas B., additional, Thompson, Chelsea, additional, Hanisco, Thomas F., additional, Blake, Donald, additional, Blake, Nicola J., additional, Apel, Eric C., additional, Hornbrook, Rebecca S., additional, Elkins, James W., additional, Hintsa, Eric J., additional, Moore, Fred L., additional, and Wofsy, Steven, additional
- Published
- 2021
- Full Text
- View/download PDF
50. Heterogeneity and Chemical Reactivity of the Remote Troposphere defined by Aircraft Measurements
- Author
-
Guo, Hao, primary, Flynn, Clare M., additional, Prather, Michael J., additional, Strode, Sarah A., additional, Steenrod, Stephen D., additional, Emmons, Louisa, additional, Lacey, Forrest, additional, Lamarque, Jean-Francois, additional, Fiore, Arlene M., additional, Correa, Gus, additional, Murray, Lee T., additional, Wolfe, Glenn M., additional, St. Clair, Jason M., additional, Kim, Michelle, additional, Crounse, John, additional, Diskin, Glenn, additional, DiGangi, Joshua, additional, Daube, Bruce C., additional, Commane, Roisin, additional, McKain, Kathryn, additional, Peischl, Jeff, additional, Ryerson, Thomas B., additional, Thompson, Chelsea, additional, Hanisco, Thomas F., additional, Blake, Donald, additional, Blake, Nicola J., additional, Apel, Eric C., additional, Hornbrook, Rebecca S., additional, Elkins, James W., additional, Hintsa, Eric J., additional, Moore, Fred L., additional, and Wofsy, Steven, additional
- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.