Abstract
Abstract. Supraglacial lakes represent an ephemeral storage buffer for meltwater runoff and lead to significant, yet short-lived, episodes of ice-flow acceleration by decanting large meltwater and energy fluxes into the ice sheet's hydrological system. Here, a methodology for calculating lake volume is used to quantify storage and drainage across Russell Glacier, West Greenland, between 2002 and 2012. Using 502 MODIS scenes, water volume at ~200 seasonally occurring lakes was derived using a depth–reflectance relationship, which was independently calibrated and field validated against lake bathymetry. The inland expansion of lakes is strongly correlated with air temperature: during the record melt years of 2010 and 2012, lakes formed and drained earlier, attaining their maximum volume 38 and 20 days earlier than the 11 yr mean, as well as occupying a greater area and forming at higher elevations (> 1800 m) than previously. Despite occupying under 2% of the study area, lakes delay the transmission of up to 7–13% of the bulk meltwater discharged. Although the results are subject to an observational bias caused by periods of cloud cover, we estimate that across Russell Glacier, 28% of supraglacial lakes drain rapidly (< 4 days). Clustering of such events in space and time suggests a synoptic trigger mechanism. Further, we find no evidence to support a unifying critical size or depth-dependent drainage threshold.
Highlights
Meltwater runoff from the Greenland Ice Sheet (GrIS) has increased since the 1960s (Hanna et al, 2005) and has been linked to seasonal ice-flow variability through basal hydrological forcing (Zwally et al, 2002; Joughin et al, 2008; van de Wal et al, 2008; Bartholomew et al, 2010)
The spatial pattern of seasonal flow acceleration coincides with the development of ice sheet surface hydrology (Palmer et al, 2011; Fitzpatrick et al, 2013) where SGLs play a vital role via temporary storage and routing of surface meltwater
We investigate the seasonal evolution of SGLs over Russell Glacier using 11 yr (2002–2012) of quasi-daily lake volume estimates
Summary
Meltwater runoff from the Greenland Ice Sheet (GrIS) has increased since the 1960s (Hanna et al, 2005) and has been linked to seasonal ice-flow variability through basal hydrological forcing (Zwally et al, 2002; Joughin et al, 2008; van de Wal et al, 2008; Bartholomew et al, 2010). The spatial pattern of seasonal flow acceleration coincides with the development of ice sheet surface hydrology (Palmer et al, 2011; Fitzpatrick et al, 2013) where SGLs play a vital role via temporary storage and routing of surface meltwater. SGLs, which are prevalent across the entire GrIS (Selmes et al, 2011), drain rapidly via hydraulic fracture propagation in ∼ 2 h (Das et al, 2008; Doyle et al, 2013), forming moulins that provide a direct hydraulic connection to the ice sheet bed.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
