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Rapid formation of an ice doline on Amery Ice Shelf, East Antarctica

Citation

Warner, R and Fricker, H and Adusumilli, S and Arndt, P and Kingslake, J and Spergel, J, Rapid formation of an ice doline on Amery Ice Shelf, East Antarctica, EGU General Assembly 2021 Book of Abstracts, 19-30 April 2021, online, pp. EGU21-14157. (2022) [Conference Extract]


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DOI: doi:10.5194/egusphere-egu21-14157

Abstract

Surface meltwater accumulating on Antarctica’s floating ice shelves can drive fractures through to the ocean and potentially cause their collapse, leading to enhanced ice discharge from the continent. Surface melting in Antarctica is predicted to increase significantly during coming decades, but the implications for ice shelf stability are unknown. We are still learning how meltwater forms, flows and alters the surface, and that rapid water-driven changes are not limited to summer. The southern Amery Ice Shelf in East Antarctica already has an extensive surface meltwater system and provides us with an opportunity to study melt processes in detail. We present high-resolution satellite data (imagery, ICESat-2 altimetry and elevation models from WorldView stereo-photogrammetry) revealing an abrupt change extending across ~60 km2 of the ice shelf surface in June 2019 (midwinter). We interpret this as drainage of an englacial lake through to the ocean below in less than three days. This left an uneven depression in the ice shelf surface, 11 km2 in area and as much as 80 m deep, with a bed of fractured ice: an "ice doline". The englacial lake had lain beneath the perennially ice-covered portion of a 20 km2 meltwater lake. The reduced mass loading on the floating ice shelf after the drainage event resulted in flexure, with uplift of up to 36 m around the former lake. Applying an elastic flexural model to the uplift profiles suggests the loss of 0.75 km3 of water to the ocean. In summer 2020, we observed meltwater accumulating in a new lake basin created by the flexure. ICESat-2 observations profiled a new narrow meltwater channel (20 m wide and 3 m deep), rapidly incised inside the doline as meltwater spilled over from the new lake and started refilling the depression. This study demonstrates how high-resolution geodetic measurements from ICESat-2 and WorldView can explore critical fine-scale ice shelf processes. The insights gained will greatly improve our ability to model these processes, ultimately improving the accuracy of our projections.

Item Details

Item Type:Conference Extract
Keywords:glaciology, Antarctica, ice shelves, supraglacial hydrology, hydrofracture
Research Division:Earth Sciences
Research Group:Physical geography and environmental geoscience
Research Field:Glaciology
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean ice dynamics
UTAS Author:Warner, R (Dr Roland Warner)
ID Code:154120
Year Published:2022
Deposited By:Australian Antarctic Program Partnership
Deposited On:2022-10-31
Last Modified:2022-11-02
Downloads:0

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