Non-Equilibrium Fractionation Factors for D/H and 18O/16O 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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Online Access: | https://hdl.handle.net/11250/3037770 https://doi.org/10.1029/2022JD037076 |
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ftunivbergen:oai:bora.uib.no:11250/3037770 2023-05-15T17:40:23+02:00 Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region Zannoni, Daniele Steen-Larsen, Hans Christian Peters, A.J. Wahl, Sonja Sodemann, Harald Sveinbjörnsdóttir, A.E. 2022 application/pdf https://hdl.handle.net/11250/3037770 https://doi.org/10.1029/2022JD037076 eng eng American Geophysical Union urn:issn:2169-897X https://hdl.handle.net/11250/3037770 https://doi.org/10.1029/2022JD037076 cristin:2086017 Journal of Geophysical Research (JGR): Atmospheres. 2022, 127 (21), e2022JD037076. Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright 2022 the authors e2022JD037076 Journal of Geophysical Research (JGR): Atmospheres 127 21 Journal article Peer reviewed 2022 ftunivbergen https://doi.org/10.1029/2022JD037076 2023-03-14T17:40:32Z 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 k18 = 5.2 ± 0.6‰ and k2 = 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 k18, 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. publishedVersion Article in Journal/Newspaper North West Atlantic Northwest Atlantic University of Bergen: Bergen Open Research Archive (BORA-UiB) Journal of Geophysical Research: Atmospheres 127 21 |
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Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
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ftunivbergen |
language |
English |
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 k18 = 5.2 ± 0.6‰ and k2 = 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 k18, 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. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Zannoni, Daniele Steen-Larsen, Hans Christian Peters, A.J. Wahl, Sonja Sodemann, Harald Sveinbjörnsdóttir, A.E. |
spellingShingle |
Zannoni, Daniele Steen-Larsen, Hans Christian Peters, A.J. Wahl, Sonja Sodemann, Harald Sveinbjörnsdóttir, A.E. Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region |
author_facet |
Zannoni, Daniele Steen-Larsen, Hans Christian Peters, A.J. Wahl, Sonja Sodemann, Harald Sveinbjörnsdóttir, A.E. |
author_sort |
Zannoni, Daniele |
title |
Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region |
title_short |
Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region |
title_full |
Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region |
title_fullStr |
Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region |
title_full_unstemmed |
Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region |
title_sort |
non-equilibrium fractionation factors for d/h and 18o/16o during oceanic evaporation in the north-west atlantic region |
publisher |
American Geophysical Union |
publishDate |
2022 |
url |
https://hdl.handle.net/11250/3037770 https://doi.org/10.1029/2022JD037076 |
genre |
North West Atlantic Northwest Atlantic |
genre_facet |
North West Atlantic Northwest Atlantic |
op_source |
e2022JD037076 Journal of Geophysical Research (JGR): Atmospheres 127 21 |
op_relation |
urn:issn:2169-897X https://hdl.handle.net/11250/3037770 https://doi.org/10.1029/2022JD037076 cristin:2086017 Journal of Geophysical Research (JGR): Atmospheres. 2022, 127 (21), e2022JD037076. |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright 2022 the authors |
op_doi |
https://doi.org/10.1029/2022JD037076 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
127 |
container_issue |
21 |
_version_ |
1766141287408336896 |