Preprints
https://doi.org/10.5194/bgd-11-4335-2014
https://doi.org/10.5194/bgd-11-4335-2014
18 Mar 2014
 | 18 Mar 2014
Status: this preprint was under review for the journal BG but the revision was not accepted.

The sensitivity of primary productivity to intra-seasonal mixed layer variability in the sub-Antarctic Zone of the Atlantic Ocean

W. R. Joubert, S. Swart, A. Tagliabue, S. J. Thomalla, and P. M. S. Monteiro

Abstract. The seasonal cycle of primary productivity is impacted by seasonal and intra-seasonal dynamics of the mixed layer through the changing balance between mixing and buoyancy forcing, which regulates nutrient supply and light availability. Of particular recent interest is the role of synoptic scale events in supplying nutrients, particularly iron, to the euphotic zone in the Sub Antarctic Zone (SAZ), where phytoplankton blooms occur throughout summer. In this study, we present high resolution measurements of net community production (NCP) constrained by ΔO2/Ar ratios, and mixed layer depth (MLD) in the Atlantic SAZ. We found a non-linear relationship between NCP and MLD, with the highest and most variable NCP observed in shallow MLDs (< 45 m). We propose that NCP variability in the SAZ may be driven by alternating states of synoptic-scale deepening of the mixed layer, leading to the entrainment of iron (dFe), followed by restratification, allowing rapid growth in an iron replete, high light environment. Synoptic iron fluxes into the euphotic zone based on water column dFe profiles and high resolution glider MLD data, reveal a potentially significant contribution of "new iron" which could sustain NCP throughout summer. Future process studies will help elaborate these findings further.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
W. R. Joubert, S. Swart, A. Tagliabue, S. J. Thomalla, and P. M. S. Monteiro
 
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Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
W. R. Joubert, S. Swart, A. Tagliabue, S. J. Thomalla, and P. M. S. Monteiro
W. R. Joubert, S. Swart, A. Tagliabue, S. J. Thomalla, and P. M. S. Monteiro

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