Journal of Geophysical Research: Oceans
Numerous coastal polynyas fringe the Antarctic continent and strongly inﬂuence the productivity of Antarctic shelf systems. Of the 46 Antarctic coastal polynyas documented in a recent study, the Amundsen Sea Polynya (ASP) stands out as having the highest net primary production per unit area. Incubation experiments suggest that this productivity is partly controlled by the availability of dissolved iron (dFe).As a ﬁrst step toward understanding the iron supply of the ASP, we introduce four plausible sources of dFe and simulate their steady spatial distribution using conservative numerical tracers. The modeled distributions replicate important features from observations including dFe maxima at the bottom of deep troughsand enhanced concentrations near the ice shelf fronts. A perturbation experiment with an idealized draw-down mimicking summertime biological uptake and subsequent resupply suggests that glacial meltwaterand sediment-derived dFe are the main contributors to the prebloom dFe inventory in the top 100 m of the ASP. The sediment-derived dFe depends strongly on the buoyancy-driven overturning circulation associated with the melting ice shelves (the ‘‘meltwater pump’’) to add dFe to the upper 300 m of the water column. The results support the view that ice shelf melting plays an important direct and indirect role in the dFe supply and delivery to polynyas such as the ASP.
Original Publication Citation
St-Laurent, P., Yager, P. L., Sherrell, R. M., Stammerjohn, S. E., & Dinniman, M. S. (2017). Pathways and supply of dissolved iron in the Amundsen Sea (Antarctica). Journal of Geophysical Research: Oceans, 122, 1-28. doi:10.1002/2017jc013162
St-Laurent, P.; Yager, P. L.; Sherrell, R. M.; Stammerjohn, S. E.; and Dinniman, M. S., "Pathways and Supply of Dissolved Iron in the Amundsen Sea (Antarctica)" (2017). CCPO Publications. 214.