Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean
The stable oxygen and hydrogen isotopic composition of water vapor over a water body is governed by the isotopic composition of surface water and ambient vapor, exchange and mixing processes at the water–air interface, and the local meteorological conditions. These parameters form inputs to the Crai...
Published in: | Atmospheric Chemistry and Physics |
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Language: | English |
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2020
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Online Access: | https://doi.org/10.5194/acp-20-11435-2020 https://acp.copernicus.org/articles/20/11435/2020/ |
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The stable oxygen and hydrogen isotopic composition of water vapor over a water body is governed by the isotopic composition of surface water and ambient vapor, exchange and mixing processes at the water–air interface, and the local meteorological conditions. These parameters form inputs to the Craig–Gordon models, used for predicting the isotopic composition of vapor produced from the surface water due to the evaporation process. In this study we present water vapor, surface water isotope ratios and meteorological parameters across latitudinal transects in the Southern Ocean (27.38–69.34 and 21.98–66.8 ∘ S) during two austral summers. The performance of Traditional Craig–Gordon (TCG) ( Craig and Gordon , 1965 ) and the Unified Craig–Gordon (UCG) ( Gonfiantini et al. , 2018 ) models is evaluated to predict the isotopic composition of evaporated water vapor flux in the diverse oceanic settings. The models are run for the molecular diffusivity ratios suggested by Merlivat ( 1978 ) , Cappa et al. ( 2003 ) and Pfahl and Wernli ( 2009 ) , referred to as MJ, CD and PW, respectively, and different turbulent indices ( x ), i.e., fractional contribution of molecular vs. turbulent diffusion. It is found that the <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">UCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.8</mn></mrow><mi mathvariant="normal">MJ</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="48pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="7a72526eb9d05f6bb93fd3c13dc9f8ae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00001.svg" width="48pt" height="17pt" src="acp-20-11435-2020-ie00001.png"/></svg:svg> , <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">UCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.6</mn></mrow><mi mathvariant="normal">CD</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="48pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="4c6a6b1d8487ac445cfb65a0bcbbe13d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00002.svg" width="48pt" height="17pt" src="acp-20-11435-2020-ie00002.png"/></svg:svg> , <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">TCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.6</mn></mrow><mi mathvariant="normal">MJ</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="47pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="875cc7df767fec50f321ddb394a1ecd8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00003.svg" width="47pt" height="17pt" src="acp-20-11435-2020-ie00003.png"/></svg:svg> and <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">TCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.7</mn></mrow><mi mathvariant="normal">CD</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="47pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="e4d80dd5f27d9d9d667e468bcab2161b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00004.svg" width="47pt" height="17pt" src="acp-20-11435-2020-ie00004.png"/></svg:svg> models predicted the isotopic composition that best matches with the observations. The relative contribution from locally generated and advected moisture is calculated at the water vapor sampling points, along the latitudinal transects, assigning the representative end-member isotopic compositions, and by solving the two-component mixing model. The results suggest a varying contribution of the advected westerly component, with an increasing trend up to 65 ∘ S. Beyond 65 ∘ S, the proportion of Antarctic moisture was found to be prominent and increasing linearly towards the coast. |
format |
Text |
author |
Dar, Shaakir Shabir Ghosh, Prosenjit Swaraj, Ankit Kumar, Anil |
spellingShingle |
Dar, Shaakir Shabir Ghosh, Prosenjit Swaraj, Ankit Kumar, Anil Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean |
author_facet |
Dar, Shaakir Shabir Ghosh, Prosenjit Swaraj, Ankit Kumar, Anil |
author_sort |
Dar, Shaakir Shabir |
title |
Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean |
title_short |
Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean |
title_full |
Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean |
title_fullStr |
Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean |
title_full_unstemmed |
Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean |
title_sort |
craig–gordon model validation using stable isotope ratios in water vapor over the southern ocean |
publishDate |
2020 |
url |
https://doi.org/10.5194/acp-20-11435-2020 https://acp.copernicus.org/articles/20/11435/2020/ |
geographic |
Antarctic Austral Southern Ocean |
geographic_facet |
Antarctic Austral Southern Ocean |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-20-11435-2020 https://acp.copernicus.org/articles/20/11435/2020/ |
op_doi |
https://doi.org/10.5194/acp-20-11435-2020 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
20 |
container_issue |
19 |
container_start_page |
11435 |
op_container_end_page |
11449 |
_version_ |
1766019743036211200 |
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ftcopernicus:oai:publications.copernicus.org:acp80949 2023-05-15T13:31:39+02:00 Craig–Gordon model validation using stable isotope ratios in water vapor over the Southern Ocean Dar, Shaakir Shabir Ghosh, Prosenjit Swaraj, Ankit Kumar, Anil 2020-10-06 application/pdf https://doi.org/10.5194/acp-20-11435-2020 https://acp.copernicus.org/articles/20/11435/2020/ eng eng doi:10.5194/acp-20-11435-2020 https://acp.copernicus.org/articles/20/11435/2020/ eISSN: 1680-7324 Text 2020 ftcopernicus https://doi.org/10.5194/acp-20-11435-2020 2020-10-12T16:22:14Z The stable oxygen and hydrogen isotopic composition of water vapor over a water body is governed by the isotopic composition of surface water and ambient vapor, exchange and mixing processes at the water–air interface, and the local meteorological conditions. These parameters form inputs to the Craig–Gordon models, used for predicting the isotopic composition of vapor produced from the surface water due to the evaporation process. In this study we present water vapor, surface water isotope ratios and meteorological parameters across latitudinal transects in the Southern Ocean (27.38–69.34 and 21.98–66.8 ∘ S) during two austral summers. The performance of Traditional Craig–Gordon (TCG) ( Craig and Gordon , 1965 ) and the Unified Craig–Gordon (UCG) ( Gonfiantini et al. , 2018 ) models is evaluated to predict the isotopic composition of evaporated water vapor flux in the diverse oceanic settings. The models are run for the molecular diffusivity ratios suggested by Merlivat ( 1978 ) , Cappa et al. ( 2003 ) and Pfahl and Wernli ( 2009 ) , referred to as MJ, CD and PW, respectively, and different turbulent indices ( x ), i.e., fractional contribution of molecular vs. turbulent diffusion. It is found that the <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">UCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.8</mn></mrow><mi mathvariant="normal">MJ</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="48pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="7a72526eb9d05f6bb93fd3c13dc9f8ae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00001.svg" width="48pt" height="17pt" src="acp-20-11435-2020-ie00001.png"/></svg:svg> , <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">UCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.6</mn></mrow><mi mathvariant="normal">CD</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="48pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="4c6a6b1d8487ac445cfb65a0bcbbe13d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00002.svg" width="48pt" height="17pt" src="acp-20-11435-2020-ie00002.png"/></svg:svg> , <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">TCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.6</mn></mrow><mi mathvariant="normal">MJ</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="47pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="875cc7df767fec50f321ddb394a1ecd8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00003.svg" width="47pt" height="17pt" src="acp-20-11435-2020-ie00003.png"/></svg:svg> and <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="normal">TCG</mi><mrow><mi>x</mi><mo>=</mo><mn mathvariant="normal">0.7</mn></mrow><mi mathvariant="normal">CD</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="47pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="e4d80dd5f27d9d9d667e468bcab2161b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-11435-2020-ie00004.svg" width="47pt" height="17pt" src="acp-20-11435-2020-ie00004.png"/></svg:svg> models predicted the isotopic composition that best matches with the observations. The relative contribution from locally generated and advected moisture is calculated at the water vapor sampling points, along the latitudinal transects, assigning the representative end-member isotopic compositions, and by solving the two-component mixing model. The results suggest a varying contribution of the advected westerly component, with an increasing trend up to 65 ∘ S. Beyond 65 ∘ S, the proportion of Antarctic moisture was found to be prominent and increasing linearly towards the coast. Text Antarc* Antarctic Southern Ocean Copernicus Publications: E-Journals Antarctic Austral Southern Ocean Atmospheric Chemistry and Physics 20 19 11435 11449 |