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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Community respiration (AOU) |- | '''Approach:''' ''in situ'' oxygen concentration |- | '''Context:''' ''in situ'' |- | '''Spatial scale:''' mesoscale to basin |- | '''Temporal scale:''' days..."

2026-05-11T19:13:34Z

Created page with "{{BreadcrumbsSecondaryProduction}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- __TOC__ <div class="model-box"> {| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Community respiration (AOU) |- | '''Approach:''' ''in situ'' oxygen concentration |- | '''Context:''' ''in situ'' |- | '''Spatial scale:''' mesoscale to basin |- | '''Temporal scale:''' days..."

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* [[Page authors|Page authors]]: [[PRIMO]]
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<div class="model-box">
{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;"
! Community respiration (AOU)
|-
| '''Approach:''' ''in situ'' oxygen concentration
|-
| '''Context:''' ''in situ''
|-
| '''Spatial scale:''' mesoscale to basin
|-
| '''Temporal scale:''' days to years
|-
| '''Units:''' mol O<sub>2</sub> L<sup>-1</sup>
|-
| '''Community captured:''' bulk
|-
| '''Co-measurements:''' cell abundance
|}
</div>
<div style="clear:both"></div>

== Method Overview ==

Apparent Oxygen Utilization (AOU) is the difference between the theoretical oxygen saturation concentration at a given temperature and salinity, and the measured dissolved oxygen concentration. A positive AOU indicates that net oxygen consumption has occurred since the water mass last equilibrated with the atmosphere, and therefore represents the cumulative biological and chemical oxygen demand integrated over the water's transit history. BGC-Argo profiling floats measure dissolved oxygen continuously across depth profiles, enabling autonomous, large-scale characterisation of AOU distributions without ship-based sampling.

=== Scale of measurement ===

AOU is an integrative measure: a single measurement reflects cumulative respiration over the entire time since the water mass was last at the surface, which can range from days in the upper ocean to decades in the deep ocean. Horizontally, float trajectories provide mesoscale to basin-scale coverage depending on deployment strategy. Vertically, profiling floats typically resolve the upper 2000 m.

=== Data generated ===

The primary output is dissolved O<sub>2</sub> concentration (mol O<sub>2</sub> L<sup>-1</sup>), from which AOU is calculated by subtracting the measured value from the equilibrium saturation value. AOU values are used to estimate depth-integrated or water-mass-specific respiration rates when combined with ventilation age estimates (e.g., from CFC or radiocarbon tracers).

=== Units & currency ===

Units are mol O<sub>2</sub> L<sup>-1</sup>. The currency is oxygen; conversion to carbon requires a respiratory quotient (RQ, typically 0.69–0.89 depending on substrate).

=== Sample size ===

''In situ'' measurement; no discrete sample collection is required for oxygen optode-based Argo floats.

=== Repositories & databases ===

BGC-Argo float data are publicly accessible through the Argo Global Data Assembly Centre (GDAC): [https://www.argodatamgt.org/ argodatamgt.org].

== Limitations ==

AOU reflects cumulative respiration since the last atmospheric contact, not an instantaneous rate. Converting AOU to a rate requires independent knowledge of the water mass age (ventilation timescale), which introduces uncertainty. Argo floats may cross different water masses during their drift, mixing signals from distinct biogeochemical regimes. Additionally, non-biological processes (e.g., solubility changes with temperature) can influence the oxygen saturation baseline and must be accounted for.

== Example Applications & Protocols ==

=== Classic examples ===
*

=== Recent applications ===
*

=== Common calculations/conversions ===
* AOU (µmol kg<sup>-1</sup>) = O<sub>2,sat</sub>(T, S) − O<sub>2,meas</sub>; saturation calculated from Garcia & Gordon (1992).
* Conversion to carbon: divide AOU by RQ (mol C = mol O<sub>2</sub> / RQ).

== References ==

[[Category:Main Pages|Model types]]

Respiration from BGC-Argo floats and AOU - Revision history