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Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region

Ocean isotopic evaporation models, such as the Craig‐Gordon model, rely on the description of nonequilibrium fractionation factors that are, in general, poorly constrained. To date, only a few gradient‐diffusion type measurements have been performed in ocean settings to test the validity of the comm...

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Autores principales: Zannoni, D., Steen‐Larsen, H. C., Peters, A. J., Wahl, S., Sodemann, H., Sveinbjörnsdóttir, A. E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9786641/
https://www.ncbi.nlm.nih.gov/pubmed/36582456
http://dx.doi.org/10.1029/2022JD037076
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author Zannoni, D.
Steen‐Larsen, H. C.
Peters, A. J.
Wahl, S.
Sodemann, H.
Sveinbjörnsdóttir, A. E.
author_facet Zannoni, D.
Steen‐Larsen, H. C.
Peters, A. J.
Wahl, S.
Sodemann, H.
Sveinbjörnsdóttir, A. E.
author_sort Zannoni, D.
collection PubMed
description Ocean isotopic evaporation models, such as the Craig‐Gordon model, rely on the description of nonequilibrium fractionation factors that are, in general, poorly constrained. To date, only a few gradient‐diffusion type measurements have been performed in ocean settings to test the validity of the commonly used parametrization of nonequilibrium isotopic fractionation during ocean evaporation. In this work, we present 6 months of water vapor isotopic observations collected from a meteorological tower located in the northwest Atlantic Ocean (Bermuda) with the objective of estimating nonequilibrium fractionation factors (k, ‰) for ocean evaporation and their wind speed dependency. The Keeling Plot method and Craig‐Gordon model combination were sensitive enough to resolve nonequilibrium fractionation factors during evaporation resulting into mean values of k (18) = 5.2 ± 0.6‰ and k (2) = 4.3 ± 3.4‰. Furthermore, we evaluate the relationship between k and 10‐m wind speed over the ocean. Such a relationship is expected from current evaporation theory and from laboratory experiments made in the 1970s, but observational evidence is lacking. We show that (a) in the observed wind speed range [0–10 m s(−1)], the sensitivity of k to wind speed is small, in the order of −0.2‰ m(−1) s for k (18), and (b) there is no empirical evidence for the presence of a discontinuity between smooth and rough wind speed regime during isotopic fractionation, as proposed in earlier studies. The water vapor d‐excess variability predicted under the closure assumption using the k values estimated in this study is in agreement with observations over the Atlantic Ocean.
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spelling pubmed-97866412022-12-27 Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region Zannoni, D. Steen‐Larsen, H. C. Peters, A. J. Wahl, S. Sodemann, H. Sveinbjörnsdóttir, A. E. J Geophys Res Atmos Research Article Ocean isotopic evaporation models, such as the Craig‐Gordon model, rely on the description of nonequilibrium fractionation factors that are, in general, poorly constrained. To date, only a few gradient‐diffusion type measurements have been performed in ocean settings to test the validity of the commonly used parametrization of nonequilibrium isotopic fractionation during ocean evaporation. In this work, we present 6 months of water vapor isotopic observations collected from a meteorological tower located in the northwest Atlantic Ocean (Bermuda) with the objective of estimating nonequilibrium fractionation factors (k, ‰) for ocean evaporation and their wind speed dependency. The Keeling Plot method and Craig‐Gordon model combination were sensitive enough to resolve nonequilibrium fractionation factors during evaporation resulting into mean values of k (18) = 5.2 ± 0.6‰ and k (2) = 4.3 ± 3.4‰. Furthermore, we evaluate the relationship between k and 10‐m wind speed over the ocean. Such a relationship is expected from current evaporation theory and from laboratory experiments made in the 1970s, but observational evidence is lacking. We show that (a) in the observed wind speed range [0–10 m s(−1)], the sensitivity of k to wind speed is small, in the order of −0.2‰ m(−1) s for k (18), and (b) there is no empirical evidence for the presence of a discontinuity between smooth and rough wind speed regime during isotopic fractionation, as proposed in earlier studies. The water vapor d‐excess variability predicted under the closure assumption using the k values estimated in this study is in agreement with observations over the Atlantic Ocean. John Wiley and Sons Inc. 2022-11-08 2022-11-16 /pmc/articles/PMC9786641/ /pubmed/36582456 http://dx.doi.org/10.1029/2022JD037076 Text en © 2022. The Authors. https://creativecommons.org/licenses/by/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Zannoni, D.
Steen‐Larsen, H. C.
Peters, A. J.
Wahl, S.
Sodemann, H.
Sveinbjörnsdóttir, A. E.
Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region
title Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region
title_full Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region
title_fullStr Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region
title_full_unstemmed Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region
title_short Non‐Equilibrium Fractionation Factors for D/H and (18)O/(16)O During Oceanic Evaporation in the North‐West Atlantic Region
title_sort non‐equilibrium fractionation factors for d/h and (18)o/(16)o during oceanic evaporation in the north‐west atlantic region
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9786641/
https://www.ncbi.nlm.nih.gov/pubmed/36582456
http://dx.doi.org/10.1029/2022JD037076
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