Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre

Abstract Mixed layer (ML) gross (GOP) and net (NOP) oxygen production rates based on in situ mass balances of triple oxygen isotopes (TOI) and O2/Ar are influenced by vertical transport from below, a term traditionally difficult to constrain. Here we present a new approach to estimate vertical eddy...

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Main Authors: W. Z. Haskell II, M. G. Prokopenko, R. H. R. Stanley, A. N. Knapp
Format: Article
Language:English
Published: Wiley 2016-07-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1002/2016GL069523
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author W. Z. Haskell II
M. G. Prokopenko
R. H. R. Stanley
A. N. Knapp
author_facet W. Z. Haskell II
M. G. Prokopenko
R. H. R. Stanley
A. N. Knapp
author_sort W. Z. Haskell II
collection DOAJ
description Abstract Mixed layer (ML) gross (GOP) and net (NOP) oxygen production rates based on in situ mass balances of triple oxygen isotopes (TOI) and O2/Ar are influenced by vertical transport from below, a term traditionally difficult to constrain. Here we present a new approach to estimate vertical eddy diffusivity (Kz) based on density gradients in the upper thermocline and wind speed‐based rates of turbulent shear at the ML depth. As an example, we use this Kz, verified by an independent 7Be‐based estimate, in an O2/TOI budget at a site in the oligotrophic South Pacific Gyre. NOP equaled 0.31 ± 0.16 mmol m−2 d−1 in the ML (~55–65 m depth) and 1.2 ± 0.4 mmol m−2 d−1 (80%) beneath the ML, while GOP equaled 74 ± 27 mmol m−2 d−1 (86%) in the ML and 12 ± 4 mmol m−2 d−1 (14%) below, revealing a vertical gradient in production rates unquantifiable without the Kz estimate.
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publishDate 2016-07-01
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series Geophysical Research Letters
spelling doaj-art-937fa5049c5c48ad9e69a6e278c461e92025-08-20T03:49:41ZengWileyGeophysical Research Letters0094-82761944-80072016-07-0143147590759910.1002/2016GL069523Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific GyreW. Z. Haskell II0M. G. Prokopenko1R. H. R. Stanley2A. N. Knapp3Department of Earth Sciences University of Southern California Los Angeles California USADepartment of Earth Sciences University of Southern California Los Angeles California USADepartment of Chemistry Wellesley College Wellesley Massachusetts USAEarth, Ocean, and Atmospheric Science Department Florida State University Tallahassee Florida USAAbstract Mixed layer (ML) gross (GOP) and net (NOP) oxygen production rates based on in situ mass balances of triple oxygen isotopes (TOI) and O2/Ar are influenced by vertical transport from below, a term traditionally difficult to constrain. Here we present a new approach to estimate vertical eddy diffusivity (Kz) based on density gradients in the upper thermocline and wind speed‐based rates of turbulent shear at the ML depth. As an example, we use this Kz, verified by an independent 7Be‐based estimate, in an O2/TOI budget at a site in the oligotrophic South Pacific Gyre. NOP equaled 0.31 ± 0.16 mmol m−2 d−1 in the ML (~55–65 m depth) and 1.2 ± 0.4 mmol m−2 d−1 (80%) beneath the ML, while GOP equaled 74 ± 27 mmol m−2 d−1 (86%) in the ML and 12 ± 4 mmol m−2 d−1 (14%) below, revealing a vertical gradient in production rates unquantifiable without the Kz estimate.https://doi.org/10.1002/2016GL069523net oxygen production (NOP)net community production (NCP)gross oxygen production (GOP)gross primary production (GPP)South Pacific Gyreeddy diffusivity
spellingShingle W. Z. Haskell II
M. G. Prokopenko
R. H. R. Stanley
A. N. Knapp
Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre
Geophysical Research Letters
net oxygen production (NOP)
net community production (NCP)
gross oxygen production (GOP)
gross primary production (GPP)
South Pacific Gyre
eddy diffusivity
title Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre
title_full Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre
title_fullStr Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre
title_full_unstemmed Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre
title_short Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre
title_sort estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic south pacific gyre
topic net oxygen production (NOP)
net community production (NCP)
gross oxygen production (GOP)
gross primary production (GPP)
South Pacific Gyre
eddy diffusivity
url https://doi.org/10.1002/2016GL069523
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