Preprints
https://doi.org/10.5194/tcd-9-2053-2015
https://doi.org/10.5194/tcd-9-2053-2015
26 Mar 2015
 | 26 Mar 2015
Status: this preprint was under review for the journal TC but the revision was not accepted.

Active lakes in Antarctica survive on a sedimentary substrate – Part 1: Theory

S. P. Carter, H. A. Fricker, and M. R. Siegfried

Abstract. Over the past decade satellite observations have revealed that active subglacial lake systems are widespread under the Antarctic ice sheet, including the ice streams, yet we have insufficient understanding of the lake-drainage process to incorporate it into ice sheet models. Process models for drainage of ice-dammed lakes based on conventional "R-channels" incised into the base of the ice through melting are unable to reproduce the timing and magnitude of drainage from Antarctic subglacial lakes estimated from satellite altimetry given the low hydraulic gradients along which such lakes drain. We developed a process model in which channels are mechanically eroded into deformable subglacial sediment (till) instead ("T-channel"). When applied to the known lakes of the Whillans/Mercer system, the model successfully reproduced the key characteristics of estimated lake volume changes for the period 2003–2009. If our model is realistic, it implies that most active lakes are shallow and only exist in the presence of saturated sediment, explaining why they are difficult to detect with classical radar methods. It also implies that the lake-drainage process is sensitive to the composition and strength of the underlying till, suggesting that models could be improved with a realistic treatment of sediment – interfacial water exchange.

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S. P. Carter, H. A. Fricker, and M. R. Siegfried
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
S. P. Carter, H. A. Fricker, and M. R. Siegfried
S. P. Carter, H. A. Fricker, and M. R. Siegfried

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Short summary
We develop a model that simulated the observed filling and draining of active subglacial lakes in Antarctica that suggests the may occurs by the erosion of channels into deformable subglacial sediments, that then deform shut as lake level declines. This contrasts with ice dammed alpine lakes which drain by channels incised into ice. If active subglacial lakes require deformable sediments to fill and drain as observed, then classic radar-based methods of lake detection may fail to find them.