A Puzzle of Oceanic Oxygen Utilization.

Koeve, Wolfgang and Kähler, Paul (2015) A Puzzle of Oceanic Oxygen Utilization. [Talk] In: ASLO Aquatic Sciences Meeting 2015. , 22.-27.02.2015, Granada, Spain .

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Large uncertainties exist in the quantification of the biological carbon pump of today’s ocean. The export of organic matter from the ocean’s euphotic zone is a critical benchmark number to describe the pump. Local measurements of the export flux are highly uncertain due to severe methodological issues and undersampling of the ocean. To this uncertainties the contribution of dissolved organic matter adds. The vertical integral of oxygen utilization in the interior of the ocean is considered an estimate of export production accounting for the export of both particular and dissolved organic matter. Regional oxygen utilization rates (OUR) are computed from apparent oxygen utilization (AOU) and an estimate of the time elapsed since the last contact with the atmosphere. Surprisingly the assumptions underlying this concept have not been tested rigorously. Using global ocean biogeochemical models we compare OUR computed from AOU and an ideal age tracer with an independent and perfect estimate of ocean respiration available in the model. In three different global models OUR underestimates true respiration by a factor of about three. Most of the difference is in the upper 1000m of the ocean. There are also important qualitative differences between the two independent approaches. For example, the contribution of dissolved organic matter driving oxygen utilization is largely underestimated when based on bulk tracer concentrations (AOU, DOC), the usual approach applied to observations.

Document Type: Conference or Workshop Item (Talk)
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > SFB 754
OceanRep > SFB 754 > A2
OceanRep > SFB 754 > A4
Projects: BIOACID, SFB754
Date Deposited: 16 Dec 2015 08:17
Last Modified: 23 Sep 2019 19:10
URI: http://oceanrep.geomar.de/id/eprint/30597

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