Filling and drainage of a subglacial lake beneath the Flade Isblink ice cap, northeast Greenland

Abstract

Abstract. The generation, transport, storage and drainage of meltwater play important roles in the Greenland Ice Sheet (GrIS) subglacial system. Active subglacial lakes, common features in Antarctica, have recently been detected beneath the GrIS and may impact ice sheet hydrology. Despite their potential importance, few repeat subglacial lake filling and drainage events have been identified in Greenland. Here we examine the surface elevation change of a collapse basin at the Flade Isblink ice cap, northeast Greenland, which formed due to sudden subglacial lake drainage in 2011. We estimate the subglacial lake volume evolution using multi-temporal ArcticDEM data and ICESat-2 altimetry data acquired between 2012 and 2021. Our long-term observations show that the subglacial lake was continuously filled by surface meltwater, with the basin surface rising by up to 55 m during 2012–2021, and we estimate 138.2 × 106 m3 of meltwater was transported into the subglacial lake between 2012 and 2017. A second rapid drainage event occurred in late August 2019, which induced an abrupt ice dynamic response. We find that the 2019 drainage released much less water than the 2011 event and conclude that multiple factors, such as the volume of water stored in the subglacial lake and bedrock relief, regulate the episodic filling and drainage of the lake. By comparing the surface meltwater production and the subglacial lake volume change, we find that only ∼ 64 % of the surface meltwater descended to the bed, suggesting potential processes such as meltwater refreezing and firn aquifer storage, which need to be further quantified.

Drainage and refill of an Antarctic Peninsula subglacial lake reveal an active subglacial hydrological network

“…Overall, the PICS feature conforms to Livingstone et al's (2022) descriptions of "water-filled cavities that drain rapidly beneath valley glaciers" (Fig. 7c in Livingstone et al, 2022;Willis et al, 2015;Liang et al, 2022). However, topographically analogous circular ice depressions, referred to as "ice cauldrons" (or "ice caldera") have also been recognised in areas of volcanic or geothermal activity, for example in Iceland (e.g.…”

“…2d). This pattern of rapid drainage and slow recharge has been described in subglacial lakes in Greenland (Willis et al, 2015;Livingstone et al, 2019;Liang et al, 2022).…”

“…© Google Earth Imagery date 1 January 2015, Maxar Technologies. dence of this has been provided by Liang et al (2022) who measured a transient 3-fold increase in glacier flow rates downstream of a lake discharge event in 2019. For subglacial lakes under the East Antarctic Ice Sheet, which are isolated from surface meltwater inputs, rapid drainage (and refilling) has been linked to a 10 % acceleration (and subsequent deceleration) in ice flow (Stearns et al, 2008).…”

Improved Monitoring of Subglacial Lake Activity in Greenland

“…The collapse basin above a subglacial lake on the southern dome of Flade Isblink ice cap in the northern part of Greenland (Fig. 5a) has been described by Willis et al (2015); Liang et al (2022), and we denote it Lake 4 (81.157°N, 16.613°W). Willis et al (2015) base their analysis on DEMs from stereo satellite imagery together with airborne LiDAR observations, while Liang et al (2022) investigate the subglacial lake using ArcticDEMs and ICESat-2 altimetry data between 2012 and 2021.…”

“…The lake will eventually drain when filled with enough water to resist the pressure exerted by the overlying glacial load (Chandler et al, 2013). The sudden drainage and outburst flood of a subglacial lake might temporarily affect ice flow velocities downstream from the lake location (Palmer et al, 2015;Liang et al, 2022). Therefore, the behavior of subglacial lakes is important to consider when discussing the response of the ice sheets to a warming climate (Willis et al, 2015).…”