Scientists unravel mystery of Antarctic polynya formations with groundbreaking study

Researchers have unveiled the mystery surrounding a rare phenomenon in Antarctic sea ice—an expansive opening is known as a polynya—that occurred during the winters of 2016 and 2017, nearly doubling the size of Wales.

A recent study published in Science Advances, titled "Ekman-Driven Salt Transport as a Key Mechanism for Open-Ocean Polynya Formation at Maud Rise," sheds light on the intricate processes behind the formation and persistence of this polynya, which had confounded scientists until now.

A collaborative effort between the University of Southampton, the University of Gothenburg, and the University of California San Diego, the research focused on the Maud Rise polynya, named after a submerged mountain-like feature in the Weddell Sea.

The study reveals that the polynya's formation was influenced by a complex interplay of factors, including wind patterns, ocean currents, and the unique topography of the ocean floor, facilitating the upward transport of heat and salt toward the surface.

While coastal areas typically experience yearly openings in the sea ice due to strong winds pushing the ice away, the formation of polynyas in the open ocean, far from the coast and over deep waters, is far more rare.

Lead researcher Aditya Narayanan, a Postdoctoral Research Fellow at the University of Southampton, notes the sporadic nature of the Maud Rise polynya, which was first detected in the 1970s but has occurred only intermittently since then.

The researchers attribute the formation of the polynya during 2016 and 2017 to a strengthening of the circular ocean current around the Weddell Sea, resulting in the upwelling of warm, salty water—a crucial factor in melting sea ice.

However, the persistent presence of the polynya required an additional mechanism to sustain the mixing of salt and heat at the surface, which led the researchers to identify the role of Ekman transport in moving salt onto the sea mount.

Ekman transport, characterized by water movement perpendicular to surface winds, facilitated the transfer of salt onto the northern flank of Maud Rise, where the polynya initially formed.

The study underscores the significance of polynyas in facilitating heat and carbon exchange between the ocean and the atmosphere, with long-lasting effects on regional climate and ocean circulation.

Professor Sarah Gille from the University of California San Diego emphasizes the broader implications of polynyas, highlighting their influence on global ocean dynamics and the observed reduction in Southern Ocean sea ice since 2016.

Source: Newsroom