Primary production in Antarctic polynyas plays a significant role in the sequestering of atmospheric CO2, and thus can act as a feedback in regulating global climate. In order to predict how net primary productivity (NPP) will respond to future changes in the ice-ocean system, it is first necessary to understand what limits phytoplankton growth rates in the region. Limitation can be quantified for a given polynya by measuring signatures of stress in phytoplankton or by incubation experiments; alternatively, remote sensing can be used to investigate large scale correlations between biomass and variables such as meltwater input, sea ice cover and cloud cover.
Due to macronutrient replete conditions, NPP in the Amundsen Sea Polynya (ASP) is thought to be limited by access to iron and/or light. However there remains uncertainty as to the source of iron and how it is related to high basal melt rates at nearby Dotson Ice Shelf (DIS). In this study the Biogeochemistry with Light, Iron, Nutrients and Gases model (BLING) is used within the MIT General Circulation Model (MITgcm) to simulate different regimes of iron supply in an idealised domain encompassing DIS and the ASP. Initial results suggest that the limitation state and therefore the sensitivity to change of NPP depends on the location of the iron source and on contributions from upstream melting.