Subglacial lakes and hydrology across the Ellsworth Subglacial Highlands, West Antarctica

Felipe Napoleoni,Stewart S R Jamieson,Rodrigo Zamora,Andrés Rivera,Andrew M Smith,José A Uribe,Alex M Brisbourne,Martin J Siegert,Neil Ross,Guisella Gacitúa,David G Vaughan,Michael J Bentley,Guy J G Paxman

doi:10.5194/tc-14-4507-2020

Abstract

Abstract. Subglacial water plays an important role in ice sheet dynamics and stability. Subglacial lakes are often located at the onset of ice streams and have been hypothesised to enhance ice flow downstream by lubricating the ice–bed interface. The most recent subglacial-lake inventory of Antarctica mapped nearly 400 lakes, of which ∼ 14 % are found in West Antarctica. Despite the potential importance of subglacial water for ice dynamics, there is a lack of detailed subglacial-water characterisation in West Antarctica. Using radio-echo sounding data, we analyse the ice–bed interface to detect subglacial lakes. We report 33 previously uncharted subglacial lakes and present a systematic analysis of their physical properties. This represents a ∼ 40 % increase in subglacial lakes in West Antarctica. Additionally, a new digital elevation model of basal topography of the Ellsworth Subglacial Highlands was built and used to create a hydropotential model to simulate the subglacial hydrological network. This allows us to characterise basal hydrology, determine subglacial water catchments and assess their connectivity. We show that the simulated subglacial hydrological catchments of the Rutford Ice Stream, Pine Island Glacier and Thwaites Glacier do not correspond to their ice surface catchments.

Highlights

Changes to subglacial hydrology associated with postLGM ice surface elevation changes have not been identified across the Ellsworth Subglacial Highlands (ESH), which are located within the Ellsworth–Whitmore Mountain (EWM) block (Fig. 1)
The new bed digital elevation model (DEM) of the ESH provides new detail on two major subglacial troughs – Ellsworth Trough (ET) and a parallel trough east of ET, informally referred to here as CECs Trough (CT; Fig. 4) – and shows that they are much deeper than shown in existing DEMs (e.g. Bedmap2 and BedMachine Antarctica v1)
These troughs extend parallel to the Ellsworth Mountains and are extensive linear features that appear to connect the interior of the ESH to the deep basins that lie beneath the West Antarctic Ice Sheet (WAIS)

Summary

Introduction

Subglacial water is important for ice sheet flow, with the potential to control the location of ice stream onset (e.g. Siegert and Bamber, 2000; Vaughan et al, 2007; Winsborrow et al, 2010; Wright and Siegert, 2012) by lubricating the ice base and reducing basal friction (Bell et al, 2011; Pattyn, 2010; Pattyn et al, 2016; Gudlaugsson et al, 2017). Subglacial water is important for ice sheet flow, with the potential to control the location of ice stream onset Napoleoni et al.: Subglacial hydrology in Ellsworth Subglacial Highlands ple, there is evidence of a well-organised and dynamic subglacial hydrological system which formed palaeochannels and basins on the seafloor of the present Amundsen Sea Embayment (ASE; Kirkham et al, 2019) This subglacial hydrological system was hypothesised to be caused by episodic releases of meltwater trapped in upstream subglacial lakes (Kirkham et al, 2019). A better understanding of the relationship between subglacial hydrology and ice dynamics is important for studies of ice sheet mass balance and supplies of water to the ocean, where meltwater can affect circulation and nutrient productivity (Ashmore and Bingham, 2014)

Objectives

Methods

Results

Discussion

Conclusion