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A strong low pressure feature in the Amundsen Sea and above average air pressure in the area south of Australia drove winds that led to the pattern of sea ice extent around the continent. Air temperatures at the 925 hPa level (about 2,500 feet above the surface) were up to 6 degrees Celsius (11 degrees Fahrenheit) above average within the Weddell Sea. Sea ice extent is particularly low along the western side of the Antarctic Peninsula, including the northern Weddell Sea and the central Indian Ocean sector. As a result, sea ice extent in the Antarctic is currently tracking as the third lowest, behind only 20. Extent went from being above the interdecile (ninetieth percentile) range to being below the tenth percentile for most of October. Since the Antarctic maximum sea ice extent was reached on September 1, 2021, ice extent has been in a steep decline. Sea Ice Index data.Ĭredit: National Snow and Ice Data Center The gray areas around the median line show the interquartile and interdecile ranges of the data. 2021 is shown in blue, 2020 in green, 2019 in orange, 2018 in brown, 2017 in magenta, and 2014 in dashed brown. The graph above shows Antarctic sea ice extent as of November 1, 2021, along with daily ice extent data for four previous years and the record low year. Seeing daylight in the Antarcticįigure 5. However, as the ice cover continues to thin, the ice will become more vulnerable to disruption by winds that can form such polynyas and seaward ridging and rafting of the ice. While such events have occurred before, they are rare. However, during the polynya formation events, winds helped to push the ice away from the shores, leaving open water for several days. This region contains the oldest and thickest ice in the Arctic Ocean, a result of the Beaufort Gyre circulation, which pushes the ice towards the coasts of Greenland and the Canadian Archipelago, where it compresses along the coasts. In May 2020, another large polynya formed north of Ellesmere Island (Figure 4). In February 2018, a large polynya (open water region) formed northeast of Greenland. This NASA Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 20, 2020, shows a large polynya, or open water region, that formed north of Ellesmere Island in Canada. October 2021 compared to previous yearsįigure 4. This rate of increase was larger than the 1981 to 2010 average of 89,200 square kilometers (34,400 square miles) per day. Overall, ice extent increased by 99,700 square kilometers (38,500 square miles) per day during the month of October. In particular, the strong sea level pressure gradient between the low and high sea level pressure near the Canadian Arctic Archipelago helped to funnel winds from the south over Baffin Bay, which is still ice-free, northwards towards the central Arctic Ocean (Figure 2c). Nevertheless, air temperatures at the 925 hPa level (about 2,500 feet above the surface) were above the 1981 to 2010 average, up to 8 degrees Celsius (14 degrees Fahrenheit) above average north of Greenland and the Canadian Archipelago (Figure 2b).Ībove average temperatures were related in part to unusually low sea level pressure extending from Siberia across to Alaska, coupled with above average sea level pressure northeast of Greenland extending down towards Baffin Bay. Yellows and reds indicate higher than average air pressures blues and purples indicate lower than average air pressures.Ĭredit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences LaboratoryĪs of October 31, sea ice extent is tracking higher than any year since 2015, as well as higher than observed in 2007, 2011, and 2012 (Figure 2a).Īverage monthly air temperatures were well below freezing across much of the Arctic Ocean in October, the exceptions being along the coastal regions of the Barents Sea and across the North Atlantic region. This plot shows the departure from average sea level pressure in the Arctic at the 925 hPa level, in degrees Celsius, for October 2021.