Observing and Modeling Drainage Networks from Supraglacial Lakes on Russell Glacier, West Greenland

Abstract

Formation and drainage of supraglacial lakes on the margin of the Greenland Ice Sheet (GrIS) is a crucial component of ice sheet surface ablation, development of supraglacial meltwater streams and ice dynamics. However, we don’t yet understand all of the controls on the spatio-temporal patterns of lake formation and drainage. Our study aims to investigate the processes that control the patterns of supraglacial lake filling and drainage cycles over an entire melt season on a section of the western GrIS near Russell Glacier. To do this we first determined locations of lakes using Landsat visible imagery. We found that lakes first initiated at low elevation early in the melt season, before progressing to increasingly higher elevations as the melt season progressed. Over the course of the melt season, lakes at lower elevations first drained and disappeared with higher elevation lakes disappearing later in the melt season. Based on these results, we anticipate that lakes were filling, overtopping and potentially draining through moulins throughout. To test this, we developed a simple model of supraglacial lake filling and drainage driven by surface air temperature. The model routed water downstream based on the direction of steepest slope. Preliminary results from the model show that supraglacial lakes first fill at lower elevations where it is warmer. As the melt season progresses, the isotherm where melt first occurs shifts to higher elevation, as seen in the observations. However, unlike observations, the model predicts persistent lakes at lower elevation. We anticipate that is a consequence of the fact that we have not included the possibility of moulin drainage in our model.