In the remote and hostile realm of the Amundsen Sea Embayment, West Antarctica, powerful winds known as low-level jets (LLJs) race over its coastal regions, including both the Thwaites and Pine Island ice shelves and the open ocean. These previous unknown atmospheric forces could hold the key to understanding—and predicting—the alarming melt of two critical glaciers: Pine Island and Thwaites, the latter ominously called the "Doomsday Glacier" for its potential to unleash catastrophic sea-level rise.
A recent study published in Advances in Atmospheric Sciences by researchers from the Indian Institute of Technology and the British Antarctic Survey zeroes in on powerful winds known as low-level jets (LLJs) that occur over the coastal region of the Amundsen Sea Embayment, West Antarctica, which includes both Thwaites and Pine Island glaciers, as well as the open ocean. These glaciers are currently melting at an accelerating pace, resulting in increased sea-level rise.
"We wanted to understand how often these LLJs happen and what causes them. Understanding these strong winds is critical as they could perhaps have important impacts on the redistribution of snow over both the Thwaites and Pine Island ice shelves, as well as affecting the ocean circulation and movement of sea-ice. These processes could potentially influence the rate at which Thwaites and Pine Island glaciers melt, and thus their contribution to sea-level rise." said Sai Prabala Swetha CHITTELLA, the lead author.
Earlier research has shown that LLJs often develop when cold, dense air flows down from Antarctica's high interior, which are known as katabatic winds. Swetha's new study explored whether nearby low-pressure systems, called cyclones, could also play a role in strengthening these katabatic winds even further, resulting.
To investigate this, the team used data from instruments attached to weather balloons, called radiosonde measurements, that had been launched from a ship near the Amundsen Sea Embayment coast in late summer to measure wind and temperature in the lower atmosphere. They then ran simulations using a high-resolution weather model to better understand the wind patterns responsible for the wind jets. What they found was surprising: 11 out of 22 of the radiosonde measurements showed these LLJs, and 10 of them were blowing out to sea (offshore). Additionally, their simulations showed the LLJs extending over large areas of the Amundsen Sea Embayment, resulting in substantially enhanced near-surface wind speeds over both the Thwaites and Pine Island ice shelves, as well as the open ocean. Additionally, the simulations showed that the strengthening of the katabatic winds by cyclones played a critical role in producing the jets.
"The most important thing we found is that LLJs happen often in this part of Antarctica and are usually made stronger by passing storms." said Dr Andrew Orr, one of the coauthor of the study.
What's next?
"We plan to continue our investigation of these extreme winds over this region of West Antarctica, including focusing on winter, when they are likely to be even more stronger and more frequent. Additionally, we want to also begin to investigate more explicitly the impacts of these winds on ocean circulation and movement of sea-ice in this critical region." said Dr Pranab Deb, another co-author of the study.
The researchers hope the study can help improve future predictions about melting ice and sea level rise and give scientists, policymakers, and communities more tools to plan for our changing climate.
