A new study by researchers at Wuhan University has shed light on one of East Antarctica’s most intriguing sea-ice features: the Mackenzie Polynya, an area of open water or thin ice that persists within the surrounding winter sea-ice pack.
Using satellite observations and remote-sensing techniques, the research team reconstructed the behaviour of the polynya during the austral cold season from 2008 to 2022. Their analysis found that the Mackenzie Polynya had an average area of approximately 5,110 square kilometres, while producing an estimated 50.2 cubic kilometres of new sea ice each year.
The study highlights the critical role of katabatic winds, the powerful downslope winds that descend from Antarctica’s elevated ice sheet toward the coast. These winds push newly formed sea ice away from the shoreline, repeatedly exposing open water to freezing conditions. This process fuels continuous ice production and helps maintain the polynya throughout much of the winter season.
Researchers found that wind forcing was the dominant factor controlling the size and persistence of the polynya. However, the long-term record also revealed that unusual atmospheric and oceanic conditions can alter this relationship. In 2010, an extreme thermal anomaly disrupted the typical wind-driven pattern, demonstrating that polynyas are influenced by a combination of environmental factors rather than a single process.
Although they may appear to be small gaps in the Antarctic sea-ice cover, polynyas play an outsized role in the Southern Ocean system. They are major sites of sea-ice formation, contributing to the production of dense, cold water that helps drive global ocean circulation. Open-water areas also enhance exchanges of heat, moisture and gases between the ocean and atmosphere, while creating productive habitats that can support Antarctic marine ecosystems.
The findings provide one of the most detailed multi-year assessments of the Mackenzie Polynya to date. By improving understanding of how Antarctic coastal polynyas respond to winds and climate variability, the research offers valuable insight into processes that influence sea ice, ocean circulation and the broader Antarctic environment.
The study was published in the IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (DOI: 10.1109/JSTARS.2026.3706687).