Sensitivity to Changes in the Winds of Cryosphere Contributions to Micronutrient Supply to the Surface Waters around Antarctica
Abstract
Previous studies showed that satellite-derived estimates of chlorophyll in coastal polynyas over the Antarctic continental shelf are correlated with the basal melt rate of adjacent ice shelves. Our earlier study used a 5 km resolution ocean/sea ice/ice shelf model of the Southern Ocean to examine mechanisms that supply the limiting micronutrient iron to Antarctic continental shelf surface waters. 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%. Much of this deep supply is from upward advection or mixing of iron-rich deep waters due to basal melt driven overturning circulation within ice shelf cavities. This effect is in general more important than the direct influence of iron released from melting ice shelves, but varies widely by location and in some areas, such as the Amundsen Sea, it is the primary mechanism for transporting deep iron to the surface.
We now use the same model, but forced with projected strengthened and poleward shifted southern hemisphere westerly winds (e.g. Spence et al., GRL, 2014). The wind changes decrease the sea ice around Antarctica and significantly increase the mean ice shelf basal melt. This leads to a general increase in the supply of iron to the surface waters around Antarctica, but the increase is quite spatially heterogeneous. The relative change in each iron source term with the modified winds is explored with the model.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMC069...07D
- Keywords:
-
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES;
- 0750 Sea ice;
- CRYOSPHERE;
- 4323 Human impact;
- NATURAL HAZARDS;
- 4815 Ecosystems;
- structure;
- dynamics;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL