Investigating Controls on the Formation and Distribution of Wintertime Storage of Water in Supraglacial Lakes

Abstract

Supraglacial lakes over the Greenland Ice Sheet can demonstrate multi-model drainage states. Lakes can demonstrate incomplete drainage, where residual melt can become buried under ice and snow and survive throughout the winter. We evaluate atmospheric factors that influence the propensity for the formation of buried lakes over the ice sheet. We examine the spatial and temporal occurrence and behavior of buried lakes over the Jakobshavn Isbrae and Zachariae Isstrøm outlet basins and assess the magnitude of insolation necessary to preserve melt water using a numerical lake model from 2009 to 2012. Buried lakes tend to occur at higher elevations within the ablation zone and those present at elevations > 1000 m tend to reoccur over several seasons. Lakes without buried water are relatively small (∼1 km2), whereas lakes with buried water are larger (∼6–10 km2). Lake area is correlated with the number of seasons sub-surface water persists. Buried lakes are relatively deep and associated with complex supraglacial channel networks. Winter stored water could be a precursor to the formation of supraglacial channels. Simulations of the insulation potential of accumulated snow and ice on the surface of lakes indicate substantial regional differences and inter-annual variability. With the possibility of inland migration of supraglacial lakes, buried lakes could be important in the evolution of ablation/percolation zone hydrology.

Comment on tc-2021-3

“…In all regions for both years, the average elevation of detected buried lakes is higher than for detected surface lakes (Appendix Fig. B2), which is consistent with previous work (Miles et al, 2017;Lampkin et al, 2020).…”

“…9a). Lampkin et al (2020) show that buried lakes which exist for multiple years are larger than buried lakes which only exist for a single season.…”

“…Previous studies have generally assumed that buried lakes on the GrIS develop when a surface lake partially freezes through and then gets buried by snowfall, insulating any remaining liquid water under the surface (Koenig et al, 2015;Schröder et al, 2020). Modelling efforts have confirmed that this process is sufficient to allow liquid water to exist under the ice surface throughout the winter on both the Greenland and Antarctic ice sheets (Law et al, 2020;Dunmire et al, 2020;Lampkin et al, 2020). In SW Greenland, most of the detected buried lakes had some surface meltwater within their bounds during the previous melt season (Fig.…”

Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery

“…Conventional understanding is that rapid lake drainages are confined to the summer and may be driven by active in situ hydrofracture through the lake bottom triggered by increased lake volume (Alley et al, 2005;van der Veen, 2007;Krawczynski et al, 2009;Arnold et al, 2014;Clason et al, 2015) and/or by passive fracture in response to perturbations in ice sheet flow induced by surface meltwater initially tapping the bed via nearby moulins (Stevens et al, 2015;Chudley et al, 2019). In this understanding, lakes completely or partially drain during the summer then freeze during the winter, either freezing through completely or maintaining a liquid water core (Selmes et al, 2013;Koenig et al, 2015;Miles et al, 2017;Law et al, 2020). High proglacial stream discharge anomalies outside of the summer melt season have been attributed to the release of stored water from the ice sheet (Rennermalm et al, 2013;Lampkin et al, 2020).…”

“…In this understanding, lakes completely or partially drain during the summer then freeze during the winter, either freezing through completely or maintaining a liquid water core (Selmes et al, 2013;Koenig et al, 2015;Miles et al, 2017;Law et al, 2020). High proglacial stream discharge anomalies outside of the summer melt season have been attributed to the release of stored water from the ice sheet (Rennermalm et al, 2013;Lampkin et al, 2020). On another occasion, proglacial stream evidence and the appearance of surface collapse features on the ice sheet were used to suggest that water may have been released from surface lakes in January and February of 1990 (Russell, 1993).…”