Premium
Supercooled Southern Ocean Waters
Author(s) -
Haumann F. Alexander,
Moorman Ruth,
Riser Stephen C.,
Smedsrud Lars H.,
Maksym Ted,
Wong Annie P. S.,
Wilson Earle A.,
Drucker Robert,
Talley Lynne D.,
Johnson Kenneth S.,
Key Robert M.,
Sarmiento Jorge L.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090242
Subject(s) - supercooling , freezing point , geology , sea ice , hydrography , oceanography , climatology , water mass , ice shelf , pycnocline , cryosphere , meteorology , geography , physics , thermodynamics
Abstract 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 wintertime 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.