During the month of September 2017, a large polynya called Weddell Polynya (GEOMAR, 2017) formed off the coast of Antarctica in the King Haakon VII Sea (Figure 1). A polynya is an irregularly shaped area of persistent open water in sea ice that is sustained by winds or ocean heat. On August 31, the Visible Infrared Imaging Radiometer Suite (VIIRS), onboard the NASA-NOAA Suomi NPP satellite, showed an isolated region of relatively warm surface temperatures, near 270 K, surrounded by cooler temperatures in the range of 260-265 K. By September 3, a small opening in the sea ice is observed with temperatures of 265-270 K, expanding over the region around the opening. Later in the month, by September 25, the polynya becomes evident. The polynya is larger than The Netherlands and almost the size of the U.S. state of Maine. It is the first time a polynya of this magnitude has been observed in the Weddell Sea in 40 years.

Figure 1: Top: Daily composites of VIIRS Ice Surface Temperature on August 31, September 3, and September 25. The polynya formation is circled. Bottom: Blended AMSR2 and VIIRS composites of sea ice concentration

References:

Helmholtz Centre for Ocean Research Kiel (GEOMAR), 2017, Antarctica: Return of the Weddell polynya supports Kiel climate model: After 40 years, a large ice-free area appears again in the Southern Ocean in mid-winter, ScienceDaily, 29 September 2017. (https://www.sciencedaily.com/releases/2017/09/170929093337.htm)

CBS News, “Giant hole reopens in Antarctic ice for the first time in 40 years”, https://www.cbsnews.com/news/giant-hole-reopens-in-antarctica-ice-for-the-first-time-in-40-years/.