Cause of 2017 Giant Hole in Antarctic Sea Ice Uncovered
In a recent study published in Science Advances, researchers have uncovered the causes behind the sporadic appearance of a large hole in Antarctica's sea ice, known as the Maud Rise polynya. The polynya, which first appeared in the 1970s and reemerged in 2016 and 2017, reached sizes of up to 80,000 square kilometers—comparable to the size of Switzerland. This phenomenon, observed during the Antarctic winters, prompted scientific investigation due to its significant size and impact on the ocean's heat and carbon balance.
The collaborative research effort, which included institutions such as the University of Southampton, Gothenburg, and the University of California San Diego, revealed that a combination of factors is responsible for the formation of the polynya. A stronger-than-usual circular ocean current in the Weddell Sea, known as the Weddell Gyre, brought warm, salty water from the ocean's depths closer to the surface. Turbulent eddies and the unique underwater geography near Maud Rise caused enhanced salt transport to the surface, a process facilitated by Ekman transport. This salt and heat mixture at the surface led to the melting of the sea ice and the formation of the open water area.
The study utilized a variety of data sources, including satellite imagery, observations from autonomous floats, and tracking information from marine mammals outfitted with sensors. The findings not only provide an explanation for the reoccurrence of the Maud Rise polynya but also offer insights that could help predict future changes in Antarctic sea ice, which is crucial for understanding global climate dynamics.
