Diurnal lake-level cycles on ice shelves driven by meltwater input and ocean tidal tilt

Diurnal depth cycles of decimeter scale are observed in a supraglacial lake on the McMurdo Ice Shelf, Antarctica. We evaluate two possible causes: (1) tidal tilt of the ice shelf in response to the underlying ocean tide, and (2) meltwater input variation. We find the latter to be the most likely exp...

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Bibliographic Details
Published in:Journal of Glaciology
Main Authors: Douglas R. MacAyeal, Ian C. Willis, Alison F. Banwell, Grant J. Macdonald, Becky Goodsell
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press 2020
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Online Access:https://doi.org/10.1017/jog.2019.98
https://doaj.org/article/3d30ba53d4174d379a77bc66888edb25
Description
Summary:Diurnal depth cycles of decimeter scale are observed in a supraglacial lake on the McMurdo Ice Shelf, Antarctica. We evaluate two possible causes: (1) tidal tilt of the ice shelf in response to the underlying ocean tide, and (2) meltwater input variation. We find the latter to be the most likely explanation of our observations. However, we do not rule out tidal tilt as a source of centimeter scale variations, and point to the possibility that other, larger supraglacial lake systems, particularly those on ice shelves that experience higher amplitude tidal tilts, such as in the Weddell Sea, may have depth cycles driven by ocean tide. The broader significance of diurnal cycles in meltwater depth is that, under circumstances where the ice shelf is thin, tidal-tilt amplitudes are high, and meltwater runoff rates are large, there may be associated flexure stresses that can contribute to ice-shelf fracture and destabilization. For the McMurdo Ice Shelf (~20–50 m thickness, ~ 1 m tidal amplitude and ~10 cm water-depth variations), these stresses amount to several 10's of kPa.