EGU22-1558, updated on 27 Mar 2022
https://doi.org/10.5194/egusphere-egu22-1558
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Drivers of Dense Shelf water formation in East Antarctic polynyas

Esther Portela Rodriguez1,2, Stephen R. Rintoul3,4,5, Laura Herraiz-Borreguero3,5, Fabien Roquet6, Takeshi Tamura7, Esmee van Wijk3,4, Sophie Bestley1,4, Clive McMahon1,6, and Mark Hindell1
Esther Portela Rodriguez et al.
  • 1Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7001, Australia
  • 2CNRS, LOPS, Plouzane, France (eportelanh@gmail.com)
  • 3CSIRO Oceans and Atmosphere, Hobart 7001, Australia
  • 4Australian Antarctic Program Partnership, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7001, Australia
  • 5Centre for Southern Hemisphere research (CSHOR), Australia
  • 6Department of Marine Sciences, University of Gothenburg, Gothenburg 40530, Sweden
  • 7National Institute of Polar Research, Tachikawa, Japan

Coastal polynyas are key regions of Dense Shelf Water (DSW) formation that ultimately contributes to the ventilation of the ocean abyss. However, not all polynyas form DSW. In this study, we analyse the main drivers of DSW formation in four East Antarctic polynyas: Mackenzie, Barrier, Shackelton and Vincennes Bay from west to east. Mackenzie and Barrier (in lesser extent) were the only two polynyas where DSW formation was observed while it is absent in Shackelton and Vincennes Bay in the particular years when they were best sampled. We analysed the role of Bathymetry, water-mass distribution and transformation, stratification of the water column, sea-ice production rate and associated salt advection. We found that sea ice production was highest in Mackenzie, particularly in early winter, which likely contributed to reach higher salinity than the other polynyas at the beginning of the sea ice formation season. From April to September, the total salinity change in Mackenzie polynya was lower than in the other polynyas, and the strong contribution of the brine rejection was partly offset by freshwater advection. Overall, the preconditioning in early winter in Mackenzie polynya, likely due to strong SIP in February and March was the main driver determining DSW formation in MAckenzie in contrast with the other East Antarctic polynyas.

How to cite: Portela Rodriguez, E., Rintoul, S. R., Herraiz-Borreguero, L., Roquet, F., Tamura, T., van Wijk, E., Bestley, S., McMahon, C., and Hindell, M.: Drivers of Dense Shelf water formation in East Antarctic polynyas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1558, https://doi.org/10.5194/egusphere-egu22-1558, 2022.

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