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| Titel |
Technical Note: The effect of vertical turbulent mixing on gross O2 production assessments by the triple isotopic composition of dissolved O2 |
| VerfasserIn |
E. Wurgaft, O. Shamir, A. Angert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 12 ; Nr. 10, no. 12 (2013-12-20), S.8363-8371 |
| Datensatznummer |
250085485
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| Publikation (Nr.) |
 copernicus.org/bg-10-8363-2013.pdf |
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| Zusammenfassung |
| The 17O excess (17Δ) of dissolved O2 has been used,
for over a decade, to estimate gross O2 production (G17OP) rates
in the mixed layer (ML) in many regions of the ocean. This estimate relies
on a steady-state balance of O2 fluxes, which include air–sea gas
exchange, photosynthesis and respiration but notably, not turbulent mixing
with O2 from the thermocline. In light of recent publications, which
showed that neglecting the turbulent flux of O2 from the thermocline
may lead to inaccurate G17OP estimations, we present a simple
correction for the effect of this flux on ML G17OP. The correction is
based on a turbulent-flux term between the thermocline and the ML, and use
the difference between the ML 17Δ and that of a single
data-point below the ML base. Using a numerical model and measured data we
compared turbulence-corrected G17OP rates to those calculated without
it, and tested the sensitivity of the GOP correction for turbulent flux of
O2 from the thermocline to several parameters. The main source of
uncertainty on the correction is the eddy-diffusivity coefficient, which
induces an uncertainty of ∼50%. The corrected G17OP
rates were 10–90% lower than the previously published uncorrected rates,
which implies that a large fraction of the photosynthetic O2 in the ML
is actually produced in the thermocline. |
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