Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability
Reducing uncertainty in the global carbon budget requires better quantification of ocean CO2 uptake and its temporal variability. Several methodologies for reconstructing air-sea CO2 exchange from pCO2 observations indicate larger decadal variability than estimated using ocean models. We develop a n...
Published in: | Global Biogeochemical Cycles |
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American Geophysical Union
2021
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Online Access: | https://boris.unibe.ch/166721/1/gloege_gbc21.pdf https://boris.unibe.ch/166721/ |
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ftunivbern:oai:boris.unibe.ch:166721 2023-08-20T04:09:58+02:00 Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability Gloege, Lucas McKinley, Galen A. Landschützer, Peter Fay, Amanda R. Frölicher, Thomas L. Fyfe, John C. Ilyina, Tatiana Jones, Steve Lovenduski, Nicole S. Rodgers, Keith B. Schlunegger, Sarah Takano, Yohei 2021 application/pdf https://boris.unibe.ch/166721/1/gloege_gbc21.pdf https://boris.unibe.ch/166721/ eng eng American Geophysical Union https://boris.unibe.ch/166721/ info:eu-repo/semantics/openAccess Gloege, Lucas; McKinley, Galen A.; Landschützer, Peter; Fay, Amanda R.; Frölicher, Thomas L.; Fyfe, John C.; Ilyina, Tatiana; Jones, Steve; Lovenduski, Nicole S.; Rodgers, Keith B.; Schlunegger, Sarah; Takano, Yohei (2021). Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability. Global biogeochemical cycles, 35(4) American Geophysical Union 10.1029/2020GB006788 <http://dx.doi.org/10.1029/2020GB006788> 530 Physics info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2021 ftunivbern https://doi.org/10.1029/2020GB006788 2023-07-31T22:12:37Z Reducing uncertainty in the global carbon budget requires better quantification of ocean CO2 uptake and its temporal variability. Several methodologies for reconstructing air-sea CO2 exchange from pCO2 observations indicate larger decadal variability than estimated using ocean models. We develop a new application of multiple Large Ensemble Earth system models to assess these reconstructions' ability to estimate spatiotemporal variability. With our Large Ensemble Testbed, pCO2 fields from 25 ensemble members each of four independent Earth system models are subsampled as the observations and the reconstruction is performed as it would be with real-world observations. The power of a testbed is that the perfect reconstruction is known for each of the original model fields; thus, reconstruction skill can be comprehensively assessed. We find that a neural-network approach can skillfully reconstruct air-sea CO2 fluxes when it is trained with sufficient data. Flux bias is low for the global mean and Northern Hemisphere, but can be regionally high in the Southern Hemisphere. The phase and amplitude of the seasonal cycle are accurately reconstructed outside of the tropics, but longer-term variations are reconstructed with only moderate skill. For Southern Ocean decadal variability, insufficient sampling leads to a 31% (15%:58%, interquartile range) overestimation of amplitude, and phasing is only moderately correlated with known truth (r = 0.54 [0.46:0.63]). Globally, the amplitude of decadal variability is overestimated by 21% (3%:34%). Machine learning, when supplied with sufficient data, can skillfully reconstruct ocean properties. However, data sparsity remains a fundamental limitation to quantification of decadal variability in the ocean carbon sink. Article in Journal/Newspaper Southern Ocean BORIS (Bern Open Repository and Information System, University of Bern) Southern Ocean Global Biogeochemical Cycles 35 4 |
institution |
Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
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ftunivbern |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Gloege, Lucas McKinley, Galen A. Landschützer, Peter Fay, Amanda R. Frölicher, Thomas L. Fyfe, John C. Ilyina, Tatiana Jones, Steve Lovenduski, Nicole S. Rodgers, Keith B. Schlunegger, Sarah Takano, Yohei Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability |
topic_facet |
530 Physics |
description |
Reducing uncertainty in the global carbon budget requires better quantification of ocean CO2 uptake and its temporal variability. Several methodologies for reconstructing air-sea CO2 exchange from pCO2 observations indicate larger decadal variability than estimated using ocean models. We develop a new application of multiple Large Ensemble Earth system models to assess these reconstructions' ability to estimate spatiotemporal variability. With our Large Ensemble Testbed, pCO2 fields from 25 ensemble members each of four independent Earth system models are subsampled as the observations and the reconstruction is performed as it would be with real-world observations. The power of a testbed is that the perfect reconstruction is known for each of the original model fields; thus, reconstruction skill can be comprehensively assessed. We find that a neural-network approach can skillfully reconstruct air-sea CO2 fluxes when it is trained with sufficient data. Flux bias is low for the global mean and Northern Hemisphere, but can be regionally high in the Southern Hemisphere. The phase and amplitude of the seasonal cycle are accurately reconstructed outside of the tropics, but longer-term variations are reconstructed with only moderate skill. For Southern Ocean decadal variability, insufficient sampling leads to a 31% (15%:58%, interquartile range) overestimation of amplitude, and phasing is only moderately correlated with known truth (r = 0.54 [0.46:0.63]). Globally, the amplitude of decadal variability is overestimated by 21% (3%:34%). Machine learning, when supplied with sufficient data, can skillfully reconstruct ocean properties. However, data sparsity remains a fundamental limitation to quantification of decadal variability in the ocean carbon sink. |
format |
Article in Journal/Newspaper |
author |
Gloege, Lucas McKinley, Galen A. Landschützer, Peter Fay, Amanda R. Frölicher, Thomas L. Fyfe, John C. Ilyina, Tatiana Jones, Steve Lovenduski, Nicole S. Rodgers, Keith B. Schlunegger, Sarah Takano, Yohei |
author_facet |
Gloege, Lucas McKinley, Galen A. Landschützer, Peter Fay, Amanda R. Frölicher, Thomas L. Fyfe, John C. Ilyina, Tatiana Jones, Steve Lovenduski, Nicole S. Rodgers, Keith B. Schlunegger, Sarah Takano, Yohei |
author_sort |
Gloege, Lucas |
title |
Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability |
title_short |
Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability |
title_full |
Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability |
title_fullStr |
Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability |
title_full_unstemmed |
Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability |
title_sort |
quantifying errors in observationally based estimates of ocean carbon sink variability |
publisher |
American Geophysical Union |
publishDate |
2021 |
url |
https://boris.unibe.ch/166721/1/gloege_gbc21.pdf https://boris.unibe.ch/166721/ |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Gloege, Lucas; McKinley, Galen A.; Landschützer, Peter; Fay, Amanda R.; Frölicher, Thomas L.; Fyfe, John C.; Ilyina, Tatiana; Jones, Steve; Lovenduski, Nicole S.; Rodgers, Keith B.; Schlunegger, Sarah; Takano, Yohei (2021). Quantifying Errors in Observationally Based Estimates of Ocean Carbon Sink Variability. Global biogeochemical cycles, 35(4) American Geophysical Union 10.1029/2020GB006788 <http://dx.doi.org/10.1029/2020GB006788> |
op_relation |
https://boris.unibe.ch/166721/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1029/2020GB006788 |
container_title |
Global Biogeochemical Cycles |
container_volume |
35 |
container_issue |
4 |
_version_ |
1774723766615539712 |