Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Atmospheric oxygen as a tracer for fossil fuel carbon dioxide : a sensitivity study in the UK

Chawner, Hannah ; Saboya, Eric ; Adcock, Karina E. ; Arnold, Tim LU orcid ; Artioli, Yuri ; Dylag, Caroline ; Forster, Grant L. ; Ganesan, Anita ; Graven, Heather and Lessin, Gennadi , et al. (2024) In Atmospheric Chemistry and Physics 24(7). p.4231-4252
Abstract

We investigate the use of atmospheric oxygen (O2) and carbon dioxide (CO2) measurements for the estimation of the fossil fuel component of atmospheric CO2 in the UK. Atmospheric potential oxygen (APO) - a tracer that combines O2 and CO2, minimizing the influence of terrestrial biosphere fluxes - is simulated at three sites in the UK, two of which make APO measurements. We present a set of model experiments that estimate the sensitivity of APO simulations to key inputs: fluxes from the ocean, fossil fuel flux magnitude and distribution, the APO baseline, and the exchange ratio of O2 to CO2 fluxes from fossil fuel combustion and the terrestrial biosphere. To... (More)

We investigate the use of atmospheric oxygen (O2) and carbon dioxide (CO2) measurements for the estimation of the fossil fuel component of atmospheric CO2 in the UK. Atmospheric potential oxygen (APO) - a tracer that combines O2 and CO2, minimizing the influence of terrestrial biosphere fluxes - is simulated at three sites in the UK, two of which make APO measurements. We present a set of model experiments that estimate the sensitivity of APO simulations to key inputs: fluxes from the ocean, fossil fuel flux magnitude and distribution, the APO baseline, and the exchange ratio of O2 to CO2 fluxes from fossil fuel combustion and the terrestrial biosphere. To estimate the influence of uncertainties in ocean fluxes, we compare three ocean O2 flux estimates from the NEMO-ERSEM, the ECCO-Darwin ocean model, and the Jena CarboScope (JC) APO inversion. The sensitivity of APO to fossil fuel emission magnitudes and to terrestrial biosphere and fossil fuel exchange ratios is investigated through Monte Carlo sampling within literature uncertainty ranges and by comparing different inventory estimates. We focus our model-data analysis on the year 2015 as ocean fluxes are not available for later years. As APO measurements are only available for one UK site at this time, our analysis focuses on the Weybourne station. Model-data comparisons for two additional UK sites (Heathfield and Ridge Hill) in 2021, using ocean flux climatologies, are presented in the Supplement. Of the factors that could potentially compromise simulated APO-derived fossil fuel CO2 (ffCO2) estimates, we find that the ocean O2 flux estimate has the largest overall influence at the three sites in the UK. At times, this influence is comparable in magnitude to the contribution of simulated fossil fuel CO2 to simulated APO. We find that simulations using different ocean fluxes differ from each other substantially. No single model estimate, or a model estimate that assumed zero ocean flux, provided a significantly closer fit than any other. Furthermore, the uncertainty in the ocean contribution to APO could lead to uncertainty in defining an appropriate regional background from the data. Our findings suggest that the contribution of non-terrestrial sources needs to be better accounted for in model simulations of APO in the UK to reduce the potential influence on inferred fossil fuel CO2 using APO.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and , et al. (More)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; and (Less)
publishing date
type
Contribution to journal
publication status
published
in
Atmospheric Chemistry and Physics
volume
24
issue
7
pages
22 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:85190274880
ISSN
1680-7316
DOI
10.5194/acp-24-4231-2024
language
English
LU publication?
no
additional info
Publisher Copyright: © 2024 Copernicus Publications. All rights reserved.
id
e69c85ac-107f-4879-9a4e-4095376464a8
date added to LUP
2024-10-22 10:14:14
date last changed
2025-05-07 02:26:40
@article{e69c85ac-107f-4879-9a4e-4095376464a8,
  abstract     = {{<p>We investigate the use of atmospheric oxygen (O<sub>2</sub>) and carbon dioxide (CO<sub>2</sub>) measurements for the estimation of the fossil fuel component of atmospheric CO<sub>2</sub> in the UK. Atmospheric potential oxygen (APO) - a tracer that combines O<sub>2</sub> and CO<sub>2</sub>, minimizing the influence of terrestrial biosphere fluxes - is simulated at three sites in the UK, two of which make APO measurements. We present a set of model experiments that estimate the sensitivity of APO simulations to key inputs: fluxes from the ocean, fossil fuel flux magnitude and distribution, the APO baseline, and the exchange ratio of O<sub>2</sub> to CO<sub>2</sub> fluxes from fossil fuel combustion and the terrestrial biosphere. To estimate the influence of uncertainties in ocean fluxes, we compare three ocean O<sub>2</sub> flux estimates from the NEMO-ERSEM, the ECCO-Darwin ocean model, and the Jena CarboScope (JC) APO inversion. The sensitivity of APO to fossil fuel emission magnitudes and to terrestrial biosphere and fossil fuel exchange ratios is investigated through Monte Carlo sampling within literature uncertainty ranges and by comparing different inventory estimates. We focus our model-data analysis on the year 2015 as ocean fluxes are not available for later years. As APO measurements are only available for one UK site at this time, our analysis focuses on the Weybourne station. Model-data comparisons for two additional UK sites (Heathfield and Ridge Hill) in 2021, using ocean flux climatologies, are presented in the Supplement. Of the factors that could potentially compromise simulated APO-derived fossil fuel CO<sub>2</sub> (ffCO<sub>2</sub>) estimates, we find that the ocean O<sub>2</sub> flux estimate has the largest overall influence at the three sites in the UK. At times, this influence is comparable in magnitude to the contribution of simulated fossil fuel CO<sub>2</sub> to simulated APO. We find that simulations using different ocean fluxes differ from each other substantially. No single model estimate, or a model estimate that assumed zero ocean flux, provided a significantly closer fit than any other. Furthermore, the uncertainty in the ocean contribution to APO could lead to uncertainty in defining an appropriate regional background from the data. Our findings suggest that the contribution of non-terrestrial sources needs to be better accounted for in model simulations of APO in the UK to reduce the potential influence on inferred fossil fuel CO<sub>2</sub> using APO.</p>}},
  author       = {{Chawner, Hannah and Saboya, Eric and Adcock, Karina E. and Arnold, Tim and Artioli, Yuri and Dylag, Caroline and Forster, Grant L. and Ganesan, Anita and Graven, Heather and Lessin, Gennadi and Levy, Peter and Luijkx, Ingrid T. and Manning, Alistair and Pickers, Penelope A. and Rennick, Chris and Rödenbeck, Christian and Rigby, Matthew}},
  issn         = {{1680-7316}},
  language     = {{eng}},
  month        = {{04}},
  number       = {{7}},
  pages        = {{4231--4252}},
  publisher    = {{Copernicus GmbH}},
  series       = {{Atmospheric Chemistry and Physics}},
  title        = {{Atmospheric oxygen as a tracer for fossil fuel carbon dioxide : a sensitivity study in the UK}},
  url          = {{http://dx.doi.org/10.5194/acp-24-4231-2024}},
  doi          = {{10.5194/acp-24-4231-2024}},
  volume       = {{24}},
  year         = {{2024}},
}