Supraglacial lake spatial structure in western Greenland during the 2007 ablation season

Abstract

[1] Increases in surface melt rates along the Greenland ice sheet margin have accelerated meltwater production, resulting in supraglacial lakes that can drain rapidly and enhance basal sliding. In this study, supraglacial lakes in western Greenland are mapped from multitemporal Landsat panchromatic imagery during the 2007 melt season. The analysis models lake spatial structure and establishes sequencing of drainage from 6 June through 9 August 2007. Results indicate high spatial clustering at lower elevations (between ∼100 and 700 m), with minimum lake-to-lake distances of ∼100-500 m and lake sizes <0.5 km 2 . At higher elevations (700-1200 m), clustering decreases with minimum distances on the order of 900-1400 m and lake sizes between 0.5 and 1 km 2 . Lakes at elevations above 1200 m exhibit less clustering and smaller areas. Clustering was spatially heterogeneous within elevation bands, with high clustering between ice streams and fewer lakes along shear margins. Spatial patterns of lake drainage throughout the 2007 melt season exhibit strong spatial coherency. The magnitude of clustering reveals patterns caused by surface melt production and water routing through surface streams as well as in situ drainage. Cluster patterns are influenced by proximity to crevasses fields, shear margins, as well as topographic structure.

Spatial and temporal variations in lakes on the Greenland Ice Sheet

“…Analysis of images separated by 10 d in July 2008, however, showed evidence of surface stream drainage between lakes and drainage into crevasse areas. When lakes evolve at higher elevations drainage mechanism is also established at these elevations (Bartholomew et al, 2011;Lampkin, 2011). The gradual lowering of the freezing isotherm at the end of the melt season (Fig.…”

“…Lakes can thus drain more efficiently or begin to drain more quickly after formation. Many lakes form in semi-permanent depressions established by the bottom topography (Echelmeyer et al, 1991;Lampkin, 2011). During the winter the melt water channels may close due to ice flow.…”

“…The Lakes were manually delineated in the images. Manual digitization has been recognized as an accurate tool when mapping both surface lakes (McMillan et al, 2007;Bartholomew et al, 2011;Lampkin, 2011;Lampkin and VanderBerg, 2011), glacier extents (Raup et al, 2007) and thermokarst lakes in aerial photographs (Sannel and Brown, 2010). False color composites of data in bands 1, 3 and 4 were evaluated, but did not improve on the single band lake mapping.…”

Wintertime storage of water in buried supraglacial lakes across the Greenland Ice Sheet

“…Several researchers have studied supraglacial lakes that are easily distinguishable by visible and radar satellites when they form seasonally in the ablation and percolation zones across the GrIS (Echelmeyer et al, 1991;Box and Ski, 2007;McMillan et al, 2007;Sneed and Hamilton, 2007;Sundal et al, 2009;Lampkin, 2011;Selmes et al, 2011;Tedesco and Steiner, 2011;Howat et al, 2013). Supraglacial lakes form in local topographic lows formed by bedrock depressions, which are not advected by the ice, and often reform in the same locations (Echelmeyer et al, 1991;Box and Ski, 2007;Selmes et al, 2011).…”

Spatial and temporal variability of water-filled crevasse hydrologic states along the shear margins of Jakobshavn Isbrae, Greenland

“…al., 1991;Box and Ski, 2007; McMillan et al, 2007;Sneed and Hamilton, 2007;Das et al, 2008, Sundal et al, 2009Lampkin, 2011;Selmes et al, 2011; Tedesco and Steiner, 2011;Howat et al, 2013; Koenig et al, 2015). The presence of ponded water within regions of fast flow has received little attention.…”