AUV Uncovers Stunning Images of Dotson Ice Shelf by Filip Stedt
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In 2022, an international team of researchers deployed a 20-foot-long autonomous underwater vehicle (AUV) called “Ran” to explore the uncharted area beneath the Dotson Ice Shelf in West Antarctica. The subsequent investigation unveiled the intricate dynamics contributing to accelerated melting rates between the western and eastern sectors of the ice shelf.
Upon revisiting the site in 2024 to document changes in the ice shelf, “Ran” unfortunately went missing beneath the icy depths, posing a significant setback to further exploration in this crucial climate-impacted region.
In tackling challenges, it is beneficial to approach them comprehensively from all angles. This principle holds true for understanding the effects of climate change-induced ice melt in Antarctica, which is why the International Thwaites Glacier Collaboration (ITGC) commissioned an autonomous underwater vehicle (AUV) dubbed “Ran” to delve into the cavity beneath the Dotson Ice Shelf, adjacent to the Thwaites Glacier in West Antarctica.
Over a span of 27 days, the AUV journeyed more than 600 miles, penetrating 10 miles into the cavity to study the mechanisms behind accelerated glacier melt near powerful underwater currents and to capture the topography of this pivotal ice shelf. Contrary to expectations, the examination revealed distinct differences in characteristics between the western and eastern parts of the ice shelf, with the latter being thicker and consequently melting at a slower rate.
The Ran AUV generated detailed maps of the underside of the Dotson Ice Shelf, unveiling peculiar tear-shaped features, icy plateaus, and intricate erosion patterns. The findings from this study were recently published in the journal Science Advances.
Anna Wåhlin, the lead researcher of the study, remarked, “By maneuvering the submersible into the cavity, we obtained high-resolution maps of the ice underside—akin to discovering the far side of the Moon.” Ice shelves, unlike glaciers resting on land, form part of the ocean, functioning as barriers that prevent land-based ice from flowing into the ocean and elevating sea levels, thus playing a critical role in polar ecosystems. Accessing the underside of these shelves is feasible but not without challenges.
The 20-foot-long Ran submersible employed advanced multibeam sonar technology to map the ice features using pulsed sound waves. Owing to its subantarctic location, communication with the AUV and GPS tracking were unattainable for Wåhlin and her team. Over the course of 14 missions, ranging from a few hours to over a day, Ran mapped approximately 50 square miles of ice, unveiling remarkably complex structures.
Wåhlin expressed, “The data from this mapping is extensive and requires further analysis. The intricate patterns we observed defy current models of glacier
The team made a significant discovery regarding the melt rates on the Dotson Ice Shelf, attributing the difference between the east and west sections to a phenomenon called the modified Circumpolar Deep Water (mCDW). This occurrence involves the mixing of Pacific and Indian Ocean waters with local water masses that affect the ice base. Ran’s measurements of underwater currents and the rapid melting of fractures within the glacier supported this data. Originally intending to study the nearby Thwaites glacier, the team found the environment too challenging to access and opted to focus on the Dotson Ice Shelf instead. Surveys conducted in 2022 revealed changes to the ice shelf, but the team faced a setback when Ran failed to reach the designated rendezvous point on the return trip. The team suspects that the Autonomous Underwater Vehicle (AUV) may have encountered obstacles or attracted attention from curious seals. Despite not achieving all their desired outcomes, the team obtained valuable data that highlights the importance of Ran in advancing scientific research. Lead researcher Wåhlin emphasized the significance of this research in understanding the future of Antarctica’s ice sheet and expressed hope for replacing Ran to continue their vital work.
