A global model for iodine speciation in the upper ocean

Wadley, Martin R., Stevens, David P. ORCID: https://orcid.org/0000-0002-7283-4405, Jickells, Tim D., Hughes, Claire, Chance, Rosie, Hepach, Helmke, Tinel, Liselotte and Carpenter, Lucy J. (2020) A global model for iodine speciation in the upper ocean. Global Biogeochemical Cycles, 34 (9). ISSN 0886-6236

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An ocean iodine cycling model is presented, which predicts upper ocean iodine speciation. The model comprises a three-layer advective and diffusive ocean circulation model of the upper ocean and an iodine cycling model embedded within this circulation. The two primary reservoirs of iodine are represented, iodide and iodate. Iodate is reduced to iodide in the mixed layer in association with primary production, linked by an iodine to carbon (I:C) ratio. A satisfactory model fit with observations cannot be obtained with a globally constant I:C ratio, and the best fit is obtained when the I:C ratio is dependent on sea surface temperature, increasing at low temperatures. Comparisons with observed iodide distributions show that the best model fit is obtained when oxidation of iodide back to iodate is associated with mixed layer nitrification. Sensitivity tests, where model parameters and processes are perturbed, reveal that primary productivity, mixed layer depth, oxidation, advection, surface freshwater flux, and the I:C ratio all have a role in determining surface iodide concentrations, and the timescale of iodide in the mixed layer is sufficiently long for nonlocal processes to be important. Comparisons of the modeled iodide surface field with parameterizations by other authors show good agreement in regions where observations exist but significant differences in regions without observations. This raises the question of whether the existing parameterizations are capturing the full range of processes involved in determining surface iodide and shows the urgent need for observations in regions where there are currently none.

Item Type: Article
Uncontrolled Keywords: iodine,model,ocean,global and planetary change,environmental chemistry,environmental science(all),atmospheric science ,/dk/atira/pure/subjectarea/asjc/2300/2306
Faculty \ School: Faculty of Science > School of Mathematics
Faculty of Science > School of Environmental Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Fluid and Solid Mechanics
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Depositing User: LivePure Connector
Date Deposited: 23 Jul 2020 23:47
Last Modified: 20 Mar 2023 12:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/76256
DOI: 10.1029/2019GB006467

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