Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage
<p>Top-down greenhouse gas measurements can be used to independently assess the accuracy of bottom-up emission estimates. We report atmospheric methane (CH<span class="inline-formula"><sub>4</sub></span>) mole fractions and <span class="inline-formula&...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/3595/2022/acp-22-3595-2022.pdf |
| _version_ | 1818312966235226112 |
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| author | E. Saboya E. Saboya G. Zazzeri H. Graven H. Graven A. J. Manning S. Englund Michel |
| author_facet | E. Saboya E. Saboya G. Zazzeri H. Graven H. Graven A. J. Manning S. Englund Michel |
| author_sort | E. Saboya |
| collection | DOAJ |
| description | <p>Top-down greenhouse gas measurements can be used to
independently assess the accuracy of bottom-up emission estimates. We
report atmospheric methane (CH<span class="inline-formula"><sub>4</sub></span>) mole fractions and <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> measurements from Imperial College London from early
2018 onwards using a Picarro G2201-i analyser. Measurements from March 2018 to
October 2020 were compared to simulations of CH<span class="inline-formula"><sub>4</sub></span> mole fractions and
<span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> produced using the NAME (Numerical Atmospheric-dispersion Modelling Environment) dispersion model coupled
with the UK National Atmospheric Emissions Inventory, UK NAEI, and a
global inventory, the Emissions Database for Global Atmospheric Research (EDGAR), with model spatial resolutions of <span class="inline-formula">∼</span> 2, <span class="inline-formula">∼</span> 10, and <span class="inline-formula">∼</span> 25 km. Simulation–measurement
comparisons are used to evaluate London emissions and the source
apportionment in the global (EDGAR) and UK national (NAEI) emission
inventories. Observed mole fractions were underestimated by 30 %–35 % in
the NAEI simulations. In contrast, a good correspondence between
observations and EDGAR simulations was seen. There was no correlation
between the measured and simulated <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> values for
either NAEI or EDGAR, however, suggesting the inventories' sectoral
attributions are incorrect. On average, natural gas sources accounted for
20 %–28 % of the above background CH<span class="inline-formula"><sub>4</sub></span> in the NAEI simulations and
only 6 %–9 % in the EDGAR simulations. In contrast, nearly 84 % of
isotopic source values calculated by Keeling plot analysis (using
measurement data from the afternoon) of individual pollution events were
higher than <span class="inline-formula">−</span>45 ‰, suggesting the primary CH<span class="inline-formula"><sub>4</sub></span>
sources in London are actually natural gas leaks. The simulation–observation
comparison of CH<span class="inline-formula"><sub>4</sub></span> mole fractions suggests that total emissions in
London are much higher than the NAEI estimate (0.04 Tg CH<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>)
but close to, or slightly lower than, the EDGAR estimate (0.10 Tg CH<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>). However, the simulation–observation comparison of <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> and the Keeling plot results indicate that emissions due
to natural gas leaks in London are being underestimated in both the UK NAEI
and EDGAR.</p> |
| first_indexed | 2024-12-13T08:26:15Z |
| format | Article |
| id | doaj.art-cea980f4f0244b5da244abbce8e82a8e |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-13T08:26:15Z |
| publishDate | 2022-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-cea980f4f0244b5da244abbce8e82a8e2022-12-21T23:53:54ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-03-01223595361310.5194/acp-22-3595-2022Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakageE. Saboya0E. Saboya1G. Zazzeri2H. Graven3H. Graven4A. J. Manning5S. Englund Michel6Department of Physics, Imperial College London, London, SW7 2AZ, UKGrantham Institute – Climate Change and the Environment, Imperial College London, London, SW7 2AZ, UKDepartment of Physics, Imperial College London, London, SW7 2AZ, UKDepartment of Physics, Imperial College London, London, SW7 2AZ, UKGrantham Institute – Climate Change and the Environment, Imperial College London, London, SW7 2AZ, UKUK Met Office, Exeter, EX1 3PB, UKInstitute of Arctic and Alpine Research, University of Colorado, Boulder, 80303 CO, USA<p>Top-down greenhouse gas measurements can be used to independently assess the accuracy of bottom-up emission estimates. We report atmospheric methane (CH<span class="inline-formula"><sub>4</sub></span>) mole fractions and <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> measurements from Imperial College London from early 2018 onwards using a Picarro G2201-i analyser. Measurements from March 2018 to October 2020 were compared to simulations of CH<span class="inline-formula"><sub>4</sub></span> mole fractions and <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> produced using the NAME (Numerical Atmospheric-dispersion Modelling Environment) dispersion model coupled with the UK National Atmospheric Emissions Inventory, UK NAEI, and a global inventory, the Emissions Database for Global Atmospheric Research (EDGAR), with model spatial resolutions of <span class="inline-formula">∼</span> 2, <span class="inline-formula">∼</span> 10, and <span class="inline-formula">∼</span> 25 km. Simulation–measurement comparisons are used to evaluate London emissions and the source apportionment in the global (EDGAR) and UK national (NAEI) emission inventories. Observed mole fractions were underestimated by 30 %–35 % in the NAEI simulations. In contrast, a good correspondence between observations and EDGAR simulations was seen. There was no correlation between the measured and simulated <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> values for either NAEI or EDGAR, however, suggesting the inventories' sectoral attributions are incorrect. On average, natural gas sources accounted for 20 %–28 % of the above background CH<span class="inline-formula"><sub>4</sub></span> in the NAEI simulations and only 6 %–9 % in the EDGAR simulations. In contrast, nearly 84 % of isotopic source values calculated by Keeling plot analysis (using measurement data from the afternoon) of individual pollution events were higher than <span class="inline-formula">−</span>45 ‰, suggesting the primary CH<span class="inline-formula"><sub>4</sub></span> sources in London are actually natural gas leaks. The simulation–observation comparison of CH<span class="inline-formula"><sub>4</sub></span> mole fractions suggests that total emissions in London are much higher than the NAEI estimate (0.04 Tg CH<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>) but close to, or slightly lower than, the EDGAR estimate (0.10 Tg CH<span class="inline-formula"><sub>4</sub></span> yr<span class="inline-formula"><sup>−1</sup></span>). However, the simulation–observation comparison of <span class="inline-formula"><i>δ</i><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span> and the Keeling plot results indicate that emissions due to natural gas leaks in London are being underestimated in both the UK NAEI and EDGAR.</p>https://acp.copernicus.org/articles/22/3595/2022/acp-22-3595-2022.pdf |
| spellingShingle | E. Saboya E. Saboya G. Zazzeri H. Graven H. Graven A. J. Manning S. Englund Michel Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage Atmospheric Chemistry and Physics |
| title | Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage |
| title_full | Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage |
| title_fullStr | Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage |
| title_full_unstemmed | Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage |
| title_short | Continuous CH<sub>4</sub> and <i>δ</i><sup>13</sup>CH<sub>4</sub> measurements in London demonstrate under-reported natural gas leakage |
| title_sort | continuous ch sub 4 sub and i δ i sup 13 sup ch sub 4 sub measurements in london demonstrate under reported natural gas leakage |
| url | https://acp.copernicus.org/articles/22/3595/2022/acp-22-3595-2022.pdf |
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