Isopycnal Mixing by Mesoscale Eddies Significantly Impacts Oceanic Anthropogenic Carbon Uptake

TitleIsopycnal Mixing by Mesoscale Eddies Significantly Impacts Oceanic Anthropogenic Carbon Uptake
Publication TypeJournal Article
Year of Publication2015
JournalGeophysical Research Letters
Volume42
Pages4249-4255
Date Published06/2015
Abstract / Summary

Anthropogenic carbon dioxide uptake varies across Earth System Models for reasons that have remained obscure. When varied within a single model, the lateral eddy mixing coefficient ARedi produces a range of uptake similar to the modeled range. The highest uptake, resulting from a simulation with a constant ARedi of 2400 m2/s, simulates 15% more historical carbon uptake than a model with ARedi = 400 m2/s. A sudden doubling in carbon dioxide produces a 21% range in carbon uptake across the models. Two spatially dependent representations of ARedi produce uptake that lies in the middle of the range of constant values despite predicting very large values in the subtropical gyres. One-dimensional diffusive models of the type used for integrated assessments can be fit to the simulations, with ARedi accounting for a substantial fraction of the effective vertical diffusion. Such models, however, mask significant regional changes in stratification and biological carbon storage.

Journal: Geophysical Research Letters
Year of Publication: 2015
Volume: 42
Pages: 4249-4255
Date Published: 06/2015

Anthropogenic carbon dioxide uptake varies across Earth System Models for reasons that have remained obscure. When varied within a single model, the lateral eddy mixing coefficient ARedi produces a range of uptake similar to the modeled range. The highest uptake, resulting from a simulation with a constant ARedi of 2400 m2/s, simulates 15% more historical carbon uptake than a model with ARedi = 400 m2/s. A sudden doubling in carbon dioxide produces a 21% range in carbon uptake across the models. Two spatially dependent representations of ARedi produce uptake that lies in the middle of the range of constant values despite predicting very large values in the subtropical gyres. One-dimensional diffusive models of the type used for integrated assessments can be fit to the simulations, with ARedi accounting for a substantial fraction of the effective vertical diffusion. Such models, however, mask significant regional changes in stratification and biological carbon storage.

Citation:
Gnanadesikan, A, M Pradal, and R Abernathey.  2015.  "Isopycnal Mixing by Mesoscale Eddies Significantly Impacts Oceanic Anthropogenic Carbon Uptake."  Geophysical Research Letters 42: 4249-4255.