EGU21-186
https://doi.org/10.5194/egusphere-egu21-186
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Supercooled Southern Ocean Waters

F. Alexander Haumann1,2, Ruth Moorman1, Stephen C. Riser3, Lars H. Smedsrud4,5,6, Ted Maksym7, Annie P. S. Wong3, Earle A. Wilson8, Robert Drucker3, Lynne D. Talley9, Kenneth S. Johnson10, Robert M. Key1, and Jorge L. Sarmiento1
F. Alexander Haumann et al.
  • 1Princeton University, Atmospheric and Oceanic Sciences Program, Atmospheric and Oceanic Sciences Program, Princeton, United States of America (alexander.haumann@gmail.com)
  • 2British Antarctic Survey, Cambridge, UK
  • 3School of Oceanography, University of Washington, Seattle, WA, USA
  • 4Geophysical Institute, University of Bergen, Bergen, Norway
  • 5Bjerknes Centre for Climate Research, Bergen, Norway
  • 6University Centre in Svalbard, Longyearbyen, Svalbard
  • 7Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
  • 8Environmental Sciences and Engineering, California Institute of Technology, Pasadena, CA, USA
  • 9Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
  • 10Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA

In cold polar waters, temperatures sometimes drop below the freezing point, a process referred to as supercooling. However, observational challenges in polar regions limit our understanding of the spatial and temporal extent of this phenomenon. We here provide observational evidence that supercooled waters are much more widespread in the seasonally ice-covered Southern Ocean than previously reported. In 5.8% of all analyzed hydrographic profiles south of 55° S, we find temperatures below the surface freezing point (‘potential’ supercooling), and half of these have temperatures below the local freezing point (‘in-situ’ supercooling). Their occurrence doubles when neglecting measurement uncertainties. We attribute deep coastal-ocean supercooling to melting of Antarctic ice shelves, and surface-induced supercooling in the seasonal sea-ice region to winter-time sea-ice formation. The latter supercooling type can extend down to the permanent pycnocline due to convective sinking plumes—an important mechanism for vertical tracer transport and water-mass structure in the polar ocean.

How to cite: Haumann, F. A., Moorman, R., Riser, S. C., Smedsrud, L. H., Maksym, T., Wong, A. P. S., Wilson, E. A., Drucker, R., Talley, L. D., Johnson, K. S., Key, R. M., and Sarmiento, J. L.: Supercooled Southern Ocean Waters, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-186, https://doi.org/10.5194/egusphere-egu21-186, 2020.

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