Abstract
Abstract. A system of subglacial lakes drained on Thwaites Glacier from 2012–2014. To improve coverage for subsequent drainage events, we extended the elevation and ice-velocity time series on Thwaites Glacier through austral winter 2019. These new observations document a second drainage cycle in 2017/18 and identified two new lake systems located in the western tributaries of Thwaites and Haynes glaciers. In situ and satellite velocity observations show temporary < 3 % speed fluctuations associated with lake drainages. In agreement with previous studies, these observations suggest that active subglacial hydrology has little influence on thinning and retreat of Thwaites Glacier on decadal to centennial timescales.
Highlights
Subglacial lakes beneath the Antarctic Ice Sheet were first discovered more than 50 years ago (Robin et al, 1969; Oswald and Robin, 1973), they remain one of the most enigmatic components of the subglacial hydrology system
We used in situ Global Navigation Satellite System (GNSS), satellite synthetic aperture radar (SAR) and satellite radar altimetry data to derive velocity and elevation-change time series
We used the speed anomalies recorded by two long-term on-ice GNSS receivers, LTHW and UTHW, deployed on Thwaites Glacier from 2009 to present to augment Eulerian velocity products derived from Sentinel-1A and Sentinel1B synthetic aperture radar (SAR) imagery of the Thwaites Glacier catchment collected between 2015–2019 (Fig. 1)
Summary
Subglacial lakes beneath the Antarctic Ice Sheet were first discovered more than 50 years ago (Robin et al, 1969; Oswald and Robin, 1973), they remain one of the most enigmatic components of the subglacial hydrology system. Identified in ice-penetrating radar data as flat, bright specular reflectors (Oswald and Robin, 1973; Carter et al, 2007), subglacial lakes were thought to be relatively steady-state features of the basal hydrology system with little impact on the dynamics of the overlying ice on multi-year timescales.
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