Distribution and dynamics of Greenland subglacial lakes

Abstract

Few subglacial lakes have been identified beneath the Greenland Ice Sheet (GrIS) despite extensive documentation in Antarctica, where periodic release of water can impact ice flow. Here we present an ice-sheet-wide survey of Greenland subglacial lakes, identifying 54 candidates from airborne radio-echo sounding, and 2 lakes from ice-surface elevation changes. These range from 0.2–5.9 km in length, and are mostly distributed away from ice divides, beneath relatively slow-moving ice. Based on our results and previous observations, we suggest three zones of formation: stable lakes in northern and eastern regions above the Equilibrium Line Altitude (ELA) but away from the interior; hydrologically-active lakes near the ELA recharged by surface meltwater and; small, seasonally-active lakes below the ELA, which form over winter and drain during the melt season. These observations provide important constraints on the GrIS's basal thermal regime and help refine our understanding of the subglacial hydrological system.

Five decades of radioglaciology

“…This includes utilizing bed-echo strength and character to investigate water body geometry and dynamic configuration, catchment-scale drainage systems and grounding zones (Schroeder and others, 2013, 2014a; Ashmore and Bingham, 2014; Christianson and others, 2016). In Greenland, a range of studies has investigated the distribution of subglacial water, including lakes, topographically controlled seasonal storage and gradients in water near the onset of fast flow (Oswald and Gogineni, 2008; Palmer and others, 2013; Chu and others, 2016, 2018b; Jordan and others, 2018b; Oswald and others, 2018; Bowling and others, 2019). Hypersaline lakes have also been identified beneath Devon Ice Cap in Arctic Canada (Rutishauser and others, 2018).…”

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

“…The standard deviation (σ) was calculated within 40 samples around a particular point to ensure a representative number of radar observations are included. A low value of σ indicates a smooth surface is present at the base of the ice as would be expected for the surface of a water body (Rivera et al, 2015;Gacitúa et al, 2015;Carter et al, 2007;Bowling et al, 2019).…”

Brief communication: Subglacial lake drainage beneath Isunguata Sermia, West Greenland: geomorphic and ice dynamic effects

“…Spatial and temporal variations in drainage structure are controlled by the hydraulic gradient and meltwater flux. Steeper hydraulic gradients and higher meltwater fluxes close to the ice margin lead to greater channel melt rates and promote the formation of efficient channels, which can extend up to 40 km inland and evolve on seasonal timescales in response to surface meltwater inputs (Chandler et al, 2013). Low hydraulic gradients and smaller meltwater fluxes dominated by subglacial meltwater sources tend to be associated with more inefficient drainage configurations further inland (Doyle et al, 2014).…”