This climate pattern and subsequent upwelling made the ocean surface unusually saline in 2016, Campbell said, which, in turn, made it easier for the ocean water to mix vertically.
Campbell and his team drew data from two robotic, human-size floats that were deployed in the Weddell Sea by the National Science Foundation-funded Southern Ocean Carbon and Climate Observations and Modeling project (SOCCOM).
Polynyas have gotten a lot of attention lately because two very large ones opened in the Weddell Sea in 2016 and 2017; in the latter event, the open waters stretched over 115,097 square miles (298,100 square kilometers), according to an article published in April in the journal Geophysical Research Letters.
The floats drift in the currents about a mile below the ocean’s surface, Campbell said, collecting data about water temperature, salinity and carbon content.
For comparison purposes, the researchers also used year-round observations from Antarctic research vessels and even scientific seals — wild pinnipeds fitted with small instruments to collect ocean data as the animals conduct their usual travels.
Scientists, with the help of floating robots and tech-equipped seals, may now have the answer: The so-called polynyas (Russian for "open water") seem to be the result of storms and salt, new research finds.
Now, the most comprehensive look ever at the ocean conditions during polynya formation reveals that these stretches of open water grow due to short-timescale climate variations and particularly nasty weather.
When the variability shifts the winds closer and stronger, it creates more upwelling of warm, salty water from deep in the Weddell Sea to the colder, fresher ocean surface.
If that carbon enters the atmosphere via polynyas, these open-water openings could contribute slightly to climate change, Campbell said.
Whether polynyas do so is still up in the air, Campbell said, but the new study should help scientists pin down more details of Antarctica’s changing climate.
But even though the winter storms of 2016 and 2017 were extreme, stormy seas are the norm in the Antarctic winter, Campbell said.
Major storms created wind and waves that mixed the water vertically, bringing up warm water from the ocean bottom that melted the sea ice.