Supercooled Southern Ocean Waters

Thursday, Oct 22, 2020

In a new paper, led by AOS Associate Research Scholar Alex Haumann, the authors find that there is much more supercooled ocean water on planet Earth than previously thought. Supercooled ocean water refers to seawater that has a temperature lower than the freezing point. In their analysis, they combine all available data from profiling floats, data collected by instrumented marine mammals, and ship-board observations in the Southern Ocean. While supercooling has been previously found in certain coastal locations due to melting of Antarctic glaciers, the researchers show here that it not only occurs in most of the coastal ocean, but also far away from the coast under the sea ice that forms in winter. This latter process has not yet been observed in the Southern Ocean. The supercooled water sinks from the surface under the sea ice down to about 100 to 200 m in the form of convective plumes. These sinking plumes might be an important process to exchange heat, carbon, oxygen and nutrients between the surface and the deeper layers of the ocean.  Largely a SOCCOM effort, the study, published in Geophysical Research Letters, includes  a number of authors from AOS: Ruth Moorman (now a graduate student at Caltech), Bob Key, Jorge Sarmiento, and Haumann.

The paper was highlighted in Nature's Research Highlights.  Nature podcast (To listen, go to minute 24:00)