Freshwater Displacement Effect on the Weddell Gyre Carbon Budget

Abstract The Weddell Gyre mediates carbon exchange between the abyssal ocean and atmosphere, which is critical to global climate. This region also features large and highly variable freshwater fluxes due to seasonal sea ice, net precipitation, and glacial melt; however, the impact of these freshwate...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Benjamin A. Taylor, Graeme A. MacGilchrist, Matthew R. Mazloff, Lynne D. Talley
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2023
Subjects:
carbon budget
freshwater
Weddell
oceanic carbon transport
sea ice
divergence
Geophysics. Cosmic physics
QC801-809
Sea ice
Southern Ocean
Online Access:https://doi.org/10.1029/2023GL103952
https://doaj.org/article/6c651a70428143c6a261c0fdab6ea01b
Description
Summary:Abstract The Weddell Gyre mediates carbon exchange between the abyssal ocean and atmosphere, which is critical to global climate. This region also features large and highly variable freshwater fluxes due to seasonal sea ice, net precipitation, and glacial melt; however, the impact of these freshwater fluxes on the regional carbon cycle has not been fully appreciated. Using a novel budget analysis of dissolved inorganic carbon (DIC) mass in the Biogeochemical Southern Ocean State Estimate, we highlight two freshwater‐driven transports. Where freshwater with minimal DIC enters the ocean, it displaces DIC‐rich seawater outwards, driving a lateral transport of 75 ± 5 Tg DIC/year. Additionally, sea ice export requires a compensating import of seawater, which carries 48 ± 11 Tg DIC/year into the gyre. Though often overlooked, these freshwater displacement effects are of leading order in the Weddell Gyre carbon budget in the state estimate and in regrouped box‐inversion estimates, with implications for evaluating basin‐scale carbon transport.

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