Dynamics of particulate organic carbon flux in a global ocean model

dc.contributor.author Lima, Ivan D.
dc.contributor.author Lam, Phoebe J.
dc.contributor.author Doney, Scott C.
dc.date.accessioned 2014-05-23T18:59:15Z
dc.date.available 2014-05-23T18:59:15Z
dc.date.issued 2014-02-27
dc.description © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 11 (2014): 1177-1198, doi:10.5194/bg-11-1177-2014. en_US
dc.description.abstract The sinking of particulate organic carbon (POC) is a key component of the ocean carbon cycle and plays an important role in the global climate system. However, the processes controlling the fraction of primary production that is exported from the euphotic zone (export ratio) and how much of it survives respiration in the mesopelagic to be sequestered in the deep ocean (transfer efficiency) are not well understood. In this study, we use a three-dimensional, coupled physical–biogeochemical model (CCSM–BEC; Community Climate System Model–ocean Biogeochemical Elemental Cycle) to investigate the processes controlling the export of particulate organic matter from the euphotic zone and its flux to depth. We also compare model results with sediment trap data and other parameterizations of POC flux to depth to evaluate model skill and gain further insight into the causes of error and uncertainty in POC flux estimates. In the model, export ratios are mainly a function of diatom relative abundance and temperature while absolute fluxes and transfer efficiency are driven by mineral ballast composition of sinking material. The temperature dependence of the POC remineralization length scale is modulated by denitrification under low O2 concentrations and lithogenic (dust) fluxes. Lithogenic material is an important control of transfer efficiency in the model, but its effect is restricted to regions of strong atmospheric dust deposition. In the remaining regions, CaCO3 content of exported material is the main factor affecting transfer efficiency. The fact that mineral ballast composition is inextricably linked to plankton community structure results in correlations between export ratios and ballast minerals fluxes (opal and CaCO3), and transfer efficiency and diatom relative abundance that do not necessarily reflect ballast or direct ecosystem effects, respectively. This suggests that it might be difficult to differentiate between ecosystem and ballast effects in observations. The model's skill in reproducing sediment trap observations is equal to or better than that of other parameterizations. However, the sparseness and relatively large uncertainties of sediment trap data makes it difficult to accurately evaluate the skill of the model and other parameterizations. More POC flux observations, over a wider range of ecological regimes, are necessary to thoroughly evaluate and test model results and better understand the processes controlling POC flux to depth in the ocean. en_US
dc.description.sponsorship Support for this work was provided by WHOI Ocean and Climate Change Institute and NSF grants OCE-0960880 and AGS-1048827. en_US
dc.format.mimetype application/pdf
dc.identifier.citation Biogeosciences 11 (2014): 1177-1198 en_US
dc.identifier.doi 10.5194/bg-11-1177-2014
dc.identifier.uri https://hdl.handle.net/1912/6674
dc.language.iso en_US en_US
dc.publisher Copernicus Publications on behalf of the European Geosciences Union en_US
dc.relation.uri https://doi.org/10.5194/bg-11-1177-2014
dc.title Dynamics of particulate organic carbon flux in a global ocean model en_US
dc.type Article en_US
dspace.entity.type Publication
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relation.isAuthorOfPublication.latestForDiscovery c09e3be3-5cc4-45bc-9b3c-30bede7efd27
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