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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2019-134
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-134
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 29 Apr 2019

Submitted as: research article | 29 Apr 2019

Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Biogeosciences (BG) and is expected to appear here in due course.

Sensitivity of ocean biogeochemistry to the iron supply from the Antarctic ice sheet explored with a biogeochemical model

Renaud Person1, Olivier Aumont1, Gurvan Madec1, Martin Vancoppenolle1, Laurent Bopp2, and Nacho Merino3 Renaud Person et al.
  • 1Laboratoire d’Océanographie et du Climat: Expérimentations et Approches Numériques (LOCEAN), IPSL, Sorbonne Université, Paris, 75005, France
  • 2Laboratoire de Météorologie Dynamique (LMD), IPSL, École Normale Supérieure – PSL Research University, CNRS, Sorbonne Université, Ecole Polytechnique, Paris, 75005, France
  • 3Université Grenoble Alpes, Institut des Geosciences de l’Environnement (IGE), CNRS, IRD, Grenoble, 38000, France

Abstract. Iron (Fe) delivery by the Antarctic Ice Sheet (AIS) through ice shelf and iceberg melting enhances primary productivity in the largely iron-limited Southern Ocean (SO). To explore this fertilization capacity, we implemented a simple representation of the AIS iron source in the global ocean biogeochemical model NEMO-PISCES. We evaluated the response of Fe, surface chlorophyll, primary production and carbon export to the magnitude and hypothesized vertical distributions of the AIS Fe fluxes. Surface Fe and chlorophyll concentrations are increased up to 25 % and 12 %, respectively, over the whole SO. The AIS Fe delivery is found to have a relatively modest impact on SO primary production and C export which are increased by 0.063 ± 0.036 PgC yr−1 and 0.028 ± 0.016 PgC yr−1, respectively. However, in highly fertilized areas, primary production and C export can be increased by up to 30 % and 42 %, respectively. Icebergs are predicted to have a much larger impact on Fe, surface chlorophyll and primary productivity than ice shelves in the SO. The response of surface Fe and chlorophyll is maximum in the Atlantic sector, northeast of the tip of the Antarctic Peninsula, and along the East Antarctic coast. The iceberg Fe delivery below the mixed layer may, depending on its assumed vertical distribution, fuel a non-negligible subsurface reservoir of Fe. The Fe supply is effective all year round and seasonal variations in iceberg melting have regional impacts which are almost negligible for annual-mean primary productivity and C export at the scale of the SO.

Renaud Person et al.
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Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Renaud Person et al.
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The Antarctic ice sheet iron source: a sensitivity study with a global ocean model R. Person https://doi.org/10.5281/zenodo.2633097

Renaud Person et al.
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Short summary
The Antarctic ice sheet is considered as a possibly important but largely overlooked source of iron (Fe). Here, we explore its fertilization capacity by evaluating the response of marine biogeochemistry to Fe release from icebergs and ice shelves in a global ocean model. Large regional impacts are simulated, leading however to modest primary production and carbon export increases at the scale of the Southern Ocean. Large uncertainties are due to low observational constraints on modeling choices.
The Antarctic ice sheet is considered as a possibly important but largely overlooked source of...
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