Reconciling the bottom-up and top-down estimates of the methane chemical sink using multiple observations
-
Published:2023-01-17
Issue:1
Volume:23
Page:789-807
-
ISSN:1680-7324
-
Container-title:Atmospheric Chemistry and Physics
-
language:en
-
Short-container-title:Atmos. Chem. Phys.
Author:
Zhao Yuanhong, Saunois Marielle, Bousquet Philippe, Lin Xin, Hegglin Michaela I.ORCID, Canadell Josep G.ORCID, Jackson Robert B.ORCID, Zheng BoORCID
Abstract
Abstract. The methane chemical sink estimated by atmospheric chemistry models (bottom-up method) is significantly larger than estimates based on
methyl chloroform (MCF) inversions (top-down method). The difference is
partly attributable to large uncertainties in hydroxyl radical (OH)
concentrations simulated by the atmospheric chemistry models used to derive
the bottom-up estimates. In this study, we propose a new approach based on
OH precursor observations and a chemical box model. This approach
contributes to improving the 3D distributions of tropospheric OH radicals obtained from atmospheric chemistry models and reconciling
bottom-up and top-down estimates of the chemical loss of atmospheric
methane. By constraining simulated OH precursors with observations, the
global mean tropospheric column-averaged air-mass-weighted OH concentration
([OH]trop-M) is ∼10×105 molec. cm−3 (which is 2×105 molec. cm−3 lower than the original model-simulated global [OH]trop-M) and agrees with that
obtained by the top-down method based on MCF inversions. With OH constrained by precursor observations, the methane chemical loss is 471–508 Tg yr−1, averaged from 2000 to 2009. The new adjusted estimate is in the range of the latest top-down estimate of the Global Carbon Project (GCP) (459–516 Tg yr−1), contrary to the bottom-up estimates that use the original model-simulated OH fields (577–612 Tg yr−1). The overestimation of global [OH]trop-M and methane chemical loss simulated by the atmospheric chemistry models is caused primarily by the models' underestimation of carbon monoxide and total ozone column, and
overestimation of nitrogen dioxide. Our results highlight that constraining
the model-simulated OH fields with available OH precursor observations can
help improve bottom-up estimates of the global methane sink.
Funder
Gordon and Betty Moore Foundation
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference74 articles.
1. Belmonte Rivas, M., Veefkind, P., Eskes, H., and Levelt, P.: OMI
tropospheric NO2 profiles from cloud slicing: constraints on surface emissions, convective transport and lightning NO2, Atmos. Chem. Phys., 15, 13519–13553, https://doi.org/10.5194/acp-15-13519-2015, 2015. 2. Boersma, K. F., Jacob, D. J., Eskes, H. J., Pinder, R. W., Wang, J., and van
der A, R. J.: Intercomparison of SCIAMACHY and OMI tropospheric NO2
columns: Observing the diurnal evolution of chemistry and emissions from
space, 113, D16S26, https://doi.org/10.1029/2007JD008816, 2008. 3. Boersma, K. F., Jacob, D. J., Trainic, M., Rudich, Y., DeSmedt, I., Dirksen,
R., and Eskes, H. J.: Validation of urban NO2 concentrations and their diurnal and seasonal variations observed from the SCIAMACHY and OMI sensors using in situ surface measurements in Israeli cities, Atmos. Chem. Phys., 9, 3867–3879, https://doi.org/10.5194/acp-9-3867-2009, 2009. 4. Boersma, K. F., Eskes, H. J., Richter, A., De Smedt, I., Lorente, A., Beirle, S., van Geffen, J. H. G. M., Zara, M., Peters, E., Van Roozendael, M., Wagner, T., Maasakkers, J. D., van der A, R. J., Nightingale, J., De Rudder, A., Irie, H., Pinardi, G., Lambert, J. C., and Compernolle, S. C.: Improving algorithms and uncertainty estimates for satellite NO2 retrievals:
results from the quality assurance for the essential climate variables (QA4ECV) project, Atmos. Meas. Tech., 11, 6651–6678,
https://doi.org/10.5194/amt-11-6651-2018, 2018. 5. Bousquet, P., Hauglustaine, D. A., Peylin, P., Carouge, C., and Ciais, P.:
Two decades of OH variability as inferred by an inversion of atmospheric
transport and chemistry of methyl chloroform, Atmos. Chem. Phys., 5,
2635–2656, https://doi.org/10.5194/acp-5-2635-2005, 2005.
Cited by
6 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|