Winters in Antarctica's Ross Sea have become stormier in recent decades, impacting sea-ice conditions and field operations, new University of Otago – Ōtākou Whakaihu Waka research shows.
Published in the journal Geophysical Research Letters, researchers used weather station data on air pressure and temperature to monitor storm behaviour from 1964 to 2024.
They found winter storms in the southwestern Ross Sea have become more frequent and intense over this period, as well as more variable – a succession of very stormy winters were interspersed every couple of years with unusually calm ones.
Antonia Radlwimmer
Lead author Antonia Radlwimmer, who completed the study as part of her PhD in Otago's Department of Physics, says when there were very stormy winters in 2019, 2022 and 2024, the fast ice (sea ice attached to land, ice shelves or grounded icebergs) in the southern sound took noticeably longer to form because the storms kept breaking out newly formed sea ice.
Co-author Dr Greg Leonard, of Otago's School of Surveying, says the researchers analysed satellite imagery to determine the timing of seasonal sea-ice formation and break-out events to infer the impact of winter storminess on sea-ice thickness.
"Intense winter storms led to a reduction in fast-ice thickness in spring/early summer because the ice forms later and has less time to thicken," Dr Leonard says.
Ms Radlwimmer says this can impact research projects.
"Spring and early summer is when we conduct field operations. Therefore, the ice we operate on is thinner than it would have been without the storms," she says.
Sea-ice conditions are critical for field operations, because if the ice is too thin then it cannot support major field camps.
This is particularly relevant in McMurdo Sound, which connects the Ross Sea to the McMurdo Ice Shelf. It is also home to New Zealand's scientific research station Scott Base and Antarctica's largest research facility, the USA's McMurdo Station.
"Also, winter sea-ice monitoring can only start at later times of year. That means our observations are missing more of the really interesting mid-winter processes," Ms Radlwimmer says.
"It would be great to develop more monitoring techniques that work in early-and mid-winter, even if there isn't safe sea-ice cover to base them from."
Publication:
Antonia L. Radlwimmer, Gregory H. Leonard, Andrew G. Pauling, Inga J. Smith, and Fabien Montiel
Geophysical Research Letters
