2023-03-03 ジョージア工科大学
このロボットは、氷の下のコンピューター制御されたミニ潜水艇で、地球外の氷の探査にも役立つと考えられている。
このロボットにより、南極大陸の氷床の下の水深1800フィートに到達し、氷の下の洞窟で見つかった異常な形状の氷とその下にある海底の痕跡を観察することができた。
今回の発見は、これまで知られていなかった氷のポンプ作用の証拠を得ることができ、海面上昇に関するモデルの改善につながると期待されている。
＜関連情報＞
- https://research.gatech.edu/robot-provides-unprecedented-views-below-antarctic-ice-shelf
- https://www.nature.com/articles/s41561-023-01129-y
カンブアイスストリーム接地帯で観測されたクレバスの再凍結と後退のサイン Crevasse refreezing and signatures of retreat observed at Kamb Ice Stream grounding zone
J. D. Lawrence,P. M. Washam,C. Stevens,C. Hulbe,H. J. Horgan,G. Dunbar,T. Calkin,C. Stewart,N. Robinson,A. D. Mullen,M. R. Meister,B. C. Hurwitz,E. Quartini,D. J. G. Dichek,A. Spears & B. E. Schmidt
Nature Geoscience Published:02 March 2023
DOI:https://doi.org/10.1038/s41561-023-01129-y
Abstract
Ice streams flowing into Ross Ice Shelf are presently responsible for around 10% of the mass flux from West Antarctica, with the noteworthy exception of Kamb Ice Stream, which stagnated in the late 1800s. The subsequent reduction in ice supply led to grounding-line retreat at the coastal margin where Kamb transitions into the floating Ross Ice Shelf. Grounding-line migration is linked to broader changes in ice-sheet mass balance and sea level, but our understanding of related ice, ocean and seafloor interactions is limited by the difficulty in accessing these remote regions. Here we report in situ observations from an underwater vehicle deployed at Kamb that show how fine-scale variability in ice and ocean structure combine to influence a diversity of ice–ocean interactions. We found a stratified water column within a tenth of a degree of freezing at the ice base and mapped basal crevasses with supercooled water and active marine ice formation. At the seafloor, we interpret parallel ridges as crevasse impressions left as the ice lifted off during grounding-line retreat. These observations from a recently ungrounded sub-shelf environment illuminate both the geomorphological signatures of past grounding-line retreat and the fine-scale sensitivity of ongoing ice–ocean interactions to ice topography.
