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Underwater Ice Terrace Observed at the Front of Glaciar Grey, a Freshwater Calving Glacier in Patagonia

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Title: Underwater Ice Terrace Observed at the Front of Glaciar Grey, a Freshwater Calving Glacier in Patagonia
Authors: Sugiyama, Shin Browse this author →KAKEN DB
Minowa, Masahiro Browse this author
Schaefer, Marius Browse this author
Keywords: glacier
calving
Patagonia
freshwater calving glacier
lake
side-scanning sonar
Issue Date: 16-Mar-2019
Publisher: American Geophysical Union
Journal Title: Geophysical research letters
Volume: 46
Issue: 5
Start Page: 2602
End Page: 2609
Publisher DOI: 10.1029/2018GL081441
Abstract: Underwater ice geometry at the front of calving glaciers provides crucial information for calving and underwater melting. In this study, we present ice geometry captured by operating a side-scanning sonar near the front of Glaciar Grey, a freshwater calving glacier in Patagonia. The observations revealed ice projecting into the lake with a substantially different structure from that of known tidewater glaciers. Terrace-like ice structures were found at several tens of meters below the water surface and extended up to 100m from the aerial ice front. The structure depicted by the sonar was confirmed when the ice front was exposed by flotation during a major calving event. We infer that buoyant force acting on the submerged ice terrace acted as a driver of the calving event. Our study demonstrates the importance of the underwater ice geometry, which affects sizable calving at the front of freshwater calving glaciers. Plain Language Summary Glaciers terminating in lakes and the ocean are in general retreating more rapidly than glaciers on land. This is because such glaciers lose ice by discharging icebergs and melting in water. The shape of the submerged part of the ice front provides important information for understanding iceberg production and melting, but measurements near the glacier front are difficult to obtain. In this study, we used a side-scanning sonar to visualize underwater ice of a lake terminating glacier in Patagonia. The observations revealed ice jutting into the lake, forming terrace-like structures several tens of meters below the water surface. The structure was significantly different from that of ocean terminating glaciers. The observation was confirmed when the ice front was detached from the glacier and exposed by flotation. Our study demonstrates that buoyant force acting on the ice terrace plays a key role in the production of large icebergs at the front of freshwater calving glaciers.
Rights: http://creativecommons.org/licenses/by-nc-nd/4.0/
Type: article
URI: http://hdl.handle.net/2115/74186
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 杉山 慎

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