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Biogeochemistry in oligotrophic ocean gyres
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Where is the downward export flux of dissolved organic carbon important in the global ocean?
Tuesday 8th @ 1430-1450, Multifunction Hall
Weilei Wang* , University of California at Irvine
Fr¨¦d¨¦ric A. C. Le Moigne, GEOMAR, Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Francois W. Primeau, University of California at Irvine
J. Keith Moore, University of California at Irvine
Presenter Email: weilei.wang@gmail.com |
| We here extrapolate the observed thorium-234 (234Th) into the global ocean by combining a global 3-D inverse circulation model with phosphorus and thorium cycling models, and estimate the global flux of particulate and dissolved organic carbon (POC and DOC). Our model shows that POC export is low in the subtropical gyres, high in eastern equatorial Pacific and east coast of the South Atlantic Ocean, and intermediate to low in the Southern Ocean. Our model also shows that DOC export is high in the Southern Ocean and high- latitude North Atlantic, intermediate in the eastern equatorial Pacific, and low in subtropical gyres. Globally, the model predicts a total carbon export (POC+DOC) of 9.61 (median, 95% CI: 9.00-10.10) Pg C/yr at 110 m, of which 64.11% (median, 95% CI: 51.05-70.27%) is due to POC export. The DOC export is spatially correlated with the difference between the winter and summer mixed-layer depth, indicating that the mixed- layer pump plays an important role in exporting DOC from the euphotic zone. Our study emphasizes on the role played by DOC export flux (mainly physical) as a means of transporting organic C out of the surface ocean. |
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