Analysis of Iron Sources in Antarctic Continental Shelf Waters
Abstract
A 5-km resolution ocean/sea ice/ice shelf model of the Southern Ocean is used to examine mechanisms that supply the limiting micronutrient iron to Antarctic continental shelf surface waters. Four sources of dissolved iron are simulated with independent tracers, assumptions about the end member concentrations, and an idealized summer biological uptake. Direct injection of iron from melting ice shelves is important to the total dissolved iron supply to surface waters, providing about 6%. However, the contribution from deep sources of iron on the shelf is much larger at 71%. The relative contribution of dissolved iron supply from basal melt driven overturning circulation within ice shelf cavities is heterogeneous around Antarctica, but at some locations, such as the Amundsen Sea, it is the primary mechanism for transporting deep dissolved iron to the surface. Correlations between satellite-derived estimates of surface chlorophyll a concentration in coastal polynyas around Antarctica and simulated estimates of dissolved iron show that the productivity of the coastal polynyas is linked to the basal melt of adjacent ice shelves. However, rather than being directly influenced by the release of iron from melting ice shelves, the larger impact results from circulation changes driven by ice shelf melt that allow other, deeper, sources of iron to be advected or mixed into the upper waters over the Antarctic continental shelf. These results indicate the potential vulnerability of coastal Antarctic ecosystems to changes in ice shelf basal melt rates.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C52A..01H
- Keywords:
-
- 0720 Glaciers;
- CRYOSPHERE;
- 0726 Ice sheets;
- CRYOSPHERE;
- 0732 Icebergs;
- CRYOSPHERE;
- 0750 Sea ice;
- CRYOSPHERE