Nonmonotonic Response of Primary Production and Export to Changes in Mixed-Layer Depth in the Southern Ocean

Llort, J, Levy, M, Sallee, JB and Tagliabue, A ORCID: 0000-0002-3572-3634 (2019) Nonmonotonic Response of Primary Production and Export to Changes in Mixed-Layer Depth in the Southern Ocean. GEOPHYSICAL RESEARCH LETTERS, 46 (6). pp. 3368-3377.

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Official URL: http://dx.doi.org/10.1029/2018gl081788

Abstract

<jats:title>Abstract</jats:title><jats:p>Ongoing and future changes in wind and temperature are predicted to alter upper ocean vertical mixing across the Southern Ocean. How these changes will affect primary production (PP) remains unclear as mixing influences the two controlling factors: light and iron. We used a large ensemble of 1‐D‐biogeochemical model simulations to explore the impacts of changes in mixed‐layer depths on PP in the Southern Ocean. In summer, shoaling mixed‐layer depth always reduced depth‐integrated PP, despite increasing production rates. In winter, shoaling mixed layers had a two‐staged impact: for moderate shoaling PP increased as light conditions improved, but more pronounced shoaling decreased iron supply, which reduced PP. The fraction of PP exported below 100 m also presented a nonmonotonic behavior. This suggests a potential future shift from a situation where reduced winter mixing increases PP and export, to a situation where PP and export may collapse if the ML shoals above a threshold depth.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	Southern Ocean, carbon export, phytoplankton, primary production, mixed-layer depth, CMIP5
Depositing User:	Symplectic Admin
Date Deposited:	16 May 2019 13:48
Last Modified:	18 Sep 2023 17:55
DOI:	10.1029/2018GL081788
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3041622