Vertical eddy iron fluxes support primary production in the open Southern Ocean

• Published in: Nature Communications
• Main Authors: Uchida, Takaya, Balwada, Dhruv, P. Abernathey, Ryan, A. McKinley, Galen, K. Smith, Shafer, Lévy, Marina
• Format: Text
• Language: English
• Published: Nature Publishing Group UK 2020
• Subjects: Article; Southern Ocean
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7048949/; http://www.ncbi.nlm.nih.gov/pubmed/32111850; https://doi.org/10.1038/s41467-020-14955-0

The primary productivity of the Southern Ocean ecosystem is limited by iron availability. Away from benthic and aeolian sources, iron reaches phytoplankton primarily when iron-rich subsurface waters enter the euphotic zone. Here, eddy-resolving physical/biogeochemical simulations of a seasonally-forced, open-Southern-Ocean ecosystem reveal that mesoscale and submesoscale isopycnal stirring effects a cross-mixed-layer-base transport of iron that sustains primary productivity. The eddy-driven iron supply and consequently productivity increase with model resolution. We show the eddy flux can be represented by specific well-tuned eddy parametrizations. Since eddy mixing rates are sensitive to wind forcing and large-scale hydrographic changes, these findings suggest a new mechanism for modulating the Southern Ocean biological pump on climate timescales.