Use of SF6 to estimate anthropogenic CO2 in the upper ocean
The highest concentrations of anthropogenic carbon (C_ant) are found in the upper layers of the world ocean. However, this is where seasonal variability of inorganic carbon and related parameters due to thermal and biological effects complicates use of back-calculation approaches for C ant . Tracer...
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ftoceanrep:oai:oceanrep.geomar.de:1617 2024-09-30T14:39:41+00:00 Use of SF6 to estimate anthropogenic CO2 in the upper ocean Tanhua, Toste Waugh, D.W. Wallace, Douglas W.R. 2008 text https://oceanrep.geomar.de/id/eprint/1617/ https://oceanrep.geomar.de/id/eprint/1617/1/2007JC004416.pdf https://doi.org/10.1029/2007JC004416 en eng AGU (American Geophysical Union) https://oceanrep.geomar.de/id/eprint/1617/1/2007JC004416.pdf Tanhua, T. , Waugh, D. W. and Wallace, D. W. R. (2008) Use of SF6 to estimate anthropogenic CO2 in the upper ocean. Open Access Journal of Geophysical Research: Oceans, 113 . C04037. DOI 10.1029/2007JC004416 <https://doi.org/10.1029/2007JC004416>. doi:10.1029/2007JC004416 info:eu-repo/semantics/openAccess Article PeerReviewed 2008 ftoceanrep https://doi.org/10.1029/2007JC004416 2024-09-04T05:04:40Z The highest concentrations of anthropogenic carbon (C_ant) are found in the upper layers of the world ocean. However, this is where seasonal variability of inorganic carbon and related parameters due to thermal and biological effects complicates use of back-calculation approaches for C ant . Tracer based approaches to C_ant estimation are unaffected by biological variability and have found wide application. However, slow-down, even reversal, of the atmospheric growth of chlorofluorocarbons (CFCs) restricts use of these tracers for C ant estimation for waters ventilated since the mid 1990s. Here we apply SF6, a tracer that continues to increase in the atmosphere, as a basis for the C_ant estimation, using samples collected in the midlatitude North Atlantic in 2004. C ant estimates derived from water mass transit time distributions (TTDs) calculated with SF6 are compared to those based on CFC-12. For recently ventilated waters (pCFC-12 > ∼450 ppt), the uncertainty of SF6 based estimates of C_ant is ∼6 μmol kg−1 less than that of CFC-12 based estimates. CFC-12 based estimates remain more reliable for older (deeper) water masses, as a result of the longer input history and more readily detectable concentrations of CFC-12. Historical data suggest that the near-surface saturation of CFC-12 has increased over time, in inverse proportion to its atmospheric growth rate. Use of a time-dependent saturation of CFC-12 in TTD calculations appears to provide more reliable estimation of C_ant . Article in Journal/Newspaper North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Journal of Geophysical Research 113 C4 |
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Open Polar |
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OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
The highest concentrations of anthropogenic carbon (C_ant) are found in the upper layers of the world ocean. However, this is where seasonal variability of inorganic carbon and related parameters due to thermal and biological effects complicates use of back-calculation approaches for C ant . Tracer based approaches to C_ant estimation are unaffected by biological variability and have found wide application. However, slow-down, even reversal, of the atmospheric growth of chlorofluorocarbons (CFCs) restricts use of these tracers for C ant estimation for waters ventilated since the mid 1990s. Here we apply SF6, a tracer that continues to increase in the atmosphere, as a basis for the C_ant estimation, using samples collected in the midlatitude North Atlantic in 2004. C ant estimates derived from water mass transit time distributions (TTDs) calculated with SF6 are compared to those based on CFC-12. For recently ventilated waters (pCFC-12 > ∼450 ppt), the uncertainty of SF6 based estimates of C_ant is ∼6 μmol kg−1 less than that of CFC-12 based estimates. CFC-12 based estimates remain more reliable for older (deeper) water masses, as a result of the longer input history and more readily detectable concentrations of CFC-12. Historical data suggest that the near-surface saturation of CFC-12 has increased over time, in inverse proportion to its atmospheric growth rate. Use of a time-dependent saturation of CFC-12 in TTD calculations appears to provide more reliable estimation of C_ant . |
format |
Article in Journal/Newspaper |
author |
Tanhua, Toste Waugh, D.W. Wallace, Douglas W.R. |
spellingShingle |
Tanhua, Toste Waugh, D.W. Wallace, Douglas W.R. Use of SF6 to estimate anthropogenic CO2 in the upper ocean |
author_facet |
Tanhua, Toste Waugh, D.W. Wallace, Douglas W.R. |
author_sort |
Tanhua, Toste |
title |
Use of SF6 to estimate anthropogenic CO2 in the upper ocean |
title_short |
Use of SF6 to estimate anthropogenic CO2 in the upper ocean |
title_full |
Use of SF6 to estimate anthropogenic CO2 in the upper ocean |
title_fullStr |
Use of SF6 to estimate anthropogenic CO2 in the upper ocean |
title_full_unstemmed |
Use of SF6 to estimate anthropogenic CO2 in the upper ocean |
title_sort |
use of sf6 to estimate anthropogenic co2 in the upper ocean |
publisher |
AGU (American Geophysical Union) |
publishDate |
2008 |
url |
https://oceanrep.geomar.de/id/eprint/1617/ https://oceanrep.geomar.de/id/eprint/1617/1/2007JC004416.pdf https://doi.org/10.1029/2007JC004416 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://oceanrep.geomar.de/id/eprint/1617/1/2007JC004416.pdf Tanhua, T. , Waugh, D. W. and Wallace, D. W. R. (2008) Use of SF6 to estimate anthropogenic CO2 in the upper ocean. Open Access Journal of Geophysical Research: Oceans, 113 . C04037. DOI 10.1029/2007JC004416 <https://doi.org/10.1029/2007JC004416>. doi:10.1029/2007JC004416 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1029/2007JC004416 |
container_title |
Journal of Geophysical Research |
container_volume |
113 |
container_issue |
C4 |
_version_ |
1811642299429421056 |