Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)

<p>Ocean circulation and the marine carbon cycle can be indirectly inferred from stable and radiogenic carbon isotope ratios (<span class="inline-formula"><i>δ</i><sup>13</sup>C</span> and <span class="inline-formula">Δ<sup>14...

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Main Authors: J. E. Dentith, R. F. Ivanovic, L. J. Gregoire, J. C. Tindall, L. F. Robinson
Format: Article
Language:English
Published: Copernicus Publications 2020-08-01
Series:Geoscientific Model Development
Online Access:https://gmd.copernicus.org/articles/13/3529/2020/gmd-13-3529-2020.pdf
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spelling doaj-a44299e19c7949e69eb5d7b0d0c92ef32020-11-25T03:04:29ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032020-08-01133529355210.5194/gmd-13-3529-2020Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)J. E. Dentith0R. F. Ivanovic1L. J. Gregoire2J. C. Tindall3L. F. Robinson4School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKSchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKSchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKSchool of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UKSchool of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, UK<p>Ocean circulation and the marine carbon cycle can be indirectly inferred from stable and radiogenic carbon isotope ratios (<span class="inline-formula"><i>δ</i><sup>13</sup>C</span> and <span class="inline-formula">Δ<sup>14</sup>C</span>, respectively), measured directly in the water column, or recorded in geological archives such as sedimentary microfossils and corals. However, interpreting these records is non-trivial because they reflect a complex interplay between physical and biogeochemical processes. By directly simulating multiple isotopic tracer fields within numerical models, we can improve our understanding of the processes that control large-scale isotope distributions and interpolate the spatiotemporal gaps in both modern and palaeo datasets. We have added the stable isotope <span class="inline-formula"><sup>13</sup>C</span> to the ocean component of the FAMOUS coupled atmosphere–ocean general circulation model, which is a valuable tool for simulating complex feedbacks between different Earth system processes on decadal to multi-millennial timescales. We tested three different biological fractionation parameterisations to account for the uncertainty associated with equilibrium fractionation during photosynthesis and used sensitivity experiments to quantify the effects of fractionation during air–sea gas exchange and primary productivity on the simulated <span class="inline-formula"><i>δ</i><sup>13</sup>C<sub>DIC</sub></span> distributions. Following a 10&thinsp;000-year pre-industrial spin-up, we simulated the Suess effect (the isotopic imprint of anthropogenic fossil fuel burning) to assess the performance of the model in replicating modern observations. Our implementation captures the large-scale structure and range of <span class="inline-formula"><i>δ</i><sup>13</sup>C<sub>DIC</sub></span> observations in the surface ocean, but the simulated values are too high at all depths, which we infer is due to biases in the biological pump. In the first instance, the new <span class="inline-formula"><sup>13</sup>C</span> tracer will therefore be useful for recalibrating both the physical and biogeochemical components of FAMOUS.</p>https://gmd.copernicus.org/articles/13/3529/2020/gmd-13-3529-2020.pdf
collection DOAJ
language English
format Article
sources DOAJ
author J. E. Dentith
R. F. Ivanovic
L. J. Gregoire
J. C. Tindall
L. F. Robinson
spellingShingle J. E. Dentith
R. F. Ivanovic
L. J. Gregoire
J. C. Tindall
L. F. Robinson
Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)
Geoscientific Model Development
author_facet J. E. Dentith
R. F. Ivanovic
L. J. Gregoire
J. C. Tindall
L. F. Robinson
author_sort J. E. Dentith
title Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)
title_short Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)
title_full Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)
title_fullStr Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)
title_full_unstemmed Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)
title_sort simulating stable carbon isotopes in the ocean component of the famous general circulation model with moses1 (xoavi)
publisher Copernicus Publications
series Geoscientific Model Development
issn 1991-959X
1991-9603
publishDate 2020-08-01
description <p>Ocean circulation and the marine carbon cycle can be indirectly inferred from stable and radiogenic carbon isotope ratios (<span class="inline-formula"><i>δ</i><sup>13</sup>C</span> and <span class="inline-formula">Δ<sup>14</sup>C</span>, respectively), measured directly in the water column, or recorded in geological archives such as sedimentary microfossils and corals. However, interpreting these records is non-trivial because they reflect a complex interplay between physical and biogeochemical processes. By directly simulating multiple isotopic tracer fields within numerical models, we can improve our understanding of the processes that control large-scale isotope distributions and interpolate the spatiotemporal gaps in both modern and palaeo datasets. We have added the stable isotope <span class="inline-formula"><sup>13</sup>C</span> to the ocean component of the FAMOUS coupled atmosphere–ocean general circulation model, which is a valuable tool for simulating complex feedbacks between different Earth system processes on decadal to multi-millennial timescales. We tested three different biological fractionation parameterisations to account for the uncertainty associated with equilibrium fractionation during photosynthesis and used sensitivity experiments to quantify the effects of fractionation during air–sea gas exchange and primary productivity on the simulated <span class="inline-formula"><i>δ</i><sup>13</sup>C<sub>DIC</sub></span> distributions. Following a 10&thinsp;000-year pre-industrial spin-up, we simulated the Suess effect (the isotopic imprint of anthropogenic fossil fuel burning) to assess the performance of the model in replicating modern observations. Our implementation captures the large-scale structure and range of <span class="inline-formula"><i>δ</i><sup>13</sup>C<sub>DIC</sub></span> observations in the surface ocean, but the simulated values are too high at all depths, which we infer is due to biases in the biological pump. In the first instance, the new <span class="inline-formula"><sup>13</sup>C</span> tracer will therefore be useful for recalibrating both the physical and biogeochemical components of FAMOUS.</p>
url https://gmd.copernicus.org/articles/13/3529/2020/gmd-13-3529-2020.pdf
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