Over-winter persistence of supraglacial lakes on the Greenland Ice Sheet: results and insights from a new model

Abstract

We present a newly developed 1-D numerical energy-balance and phase transition supraglacial lake model: GlacierLake. GlacierLake incorporates snowfall, in situ snow and ice melt, incoming water from the surrounding catchment, ice lid formation, basal freeze-up and thermal stratification. Snow cover and temperature are varied to test lake development through winter and the maximum lid thickness is recorded. Average wintertime temperatures of −2 to $-30^{\circ }{\rm C}$ and total snowfall of 0 to 3.45 m lead to a range of the maximum lid thickness from 1.2 to 2.8 m after ${\sim }250$ days, with snow cover exerting the dominant control. An initial ice temperature of $-15^{\circ }{\rm C}$ with simulated advection of cold ice from upstream results in 0.6 m of basal freeze-up. This suggests that lakes with water depths above 1.3 to 3.4 m (dependent on winter snowfall and temperature) upon lid formation will persist through winter. These buried lakes can provide a sizeable water store at the start of the melt season, expedite future lake formation and warm underlying ice even in winter.

Thermodynamics of a fast-moving Greenlandic outlet glacier revealed by fiber-optic distributed temperature sensing

“…We used a simple 1D heat diffusion model adapted from ( 66 ) to investigate temperature evolution in the region of Anomaly-208 with a vertical resolution of 0.5 m under (i) no heat inputs or sinks and (ii) heat inputs and sinks prescribed manually as square waves to maintain the anomaly at a steady state. The energy input and sink required to sustain the anomaly can be used to estimate the deformation rate.…”

Contrasting regional variability of buried meltwater extent over 2 years across the Greenland Ice Sheet

“…This analysis suggests that increasing air temperatures, which contribute to increased summer melt, will likely lead to an increase in the number and area of buried lakes and therefore an increased volume of liquid water that is stored beneath the surface during the winter. Surface lake distribution across the GrIS has expanded inland to higher elevations (Howat et al, 2013), and it is expected that surface lakes will continue to form at higher elevations as air temperatures continue to rise in the future (Leeson et al, 2015). Thus, we also expect that buried lakes will form further inland at higher elevations in a warming climate, with potential implications for changing surface hydrology and total ice loss.…”

Perennial Supraglacial Lakes in Northeast Greenland Observed by Polarimetric SAR

“…This causes a significant reduction in surface scattering, and hence, the HH-HV difference can no longer distinguish between the frozen lake water and the surrounding glacier ice. However, lakes with a water depth from several meters up to tens of meters (which is the case for many SGLs; see [17,27,[40][41][42]) have a heat capacity which allows them to stay liquid over the whole winter if they are well isolated by a significant layer of ice and snow [19].…”

“…However, when a lake freezes over and is covered by fresh snow, it cannot be identified any longer, but this does not necessarily mean that the lake has disappeared. Energy-balance and phase transition modeling demonstrated that under the climatic conditions on the GrIS, ice lids form up to a thickness of~1-3 m, but below that depth, the water stays liquid [19].…”