High resolution monitoring of Greenlandic ice marginal lakes

At present, 10% of the Greenland Ice Sheet (GrIS) margin terminates in a lake, but this is forecast to increase significantly over coming decades with ongoing retreat and thinning of the ice margin. This is important because the existence of more and larger lakes implies greater mass loss at the margin as well as an increase in dynamic thinning up-ice. At the same time, non-glacial lake surface waters worldwide have been shown to be warming yet the record of temperature change in ice-marginal lakes is extremely sparse. These ice-marginal lakes are likely to become increasingly important drivers of mass loss, and so there is an urgent need to investigate more closely the connection between their evolution and changes in the ice sheet. Therefore, a key objective is to explore the thermal properties of these lakes.

The majority of Greenland’s ice marginal lakes are small (<0.5km²) thus limiting the role of remote sensing approaches. To fully characterise and understand the detailed thermal properties of these lakes over time and space we thus developed an in-situ approach for high resolution monitoring of the temperature evolution of two Greenlandic ice marginal lakes. Our monitoring approach involved the installation of a series of thermistor strings which recorded water temperature at several locations and at a range of depths every 30 minutes for more than one year. Over the same period we deployed a series of 15 time-lapse cameras capturing hourly imagery so as to build 3D models of ice front change in response to changing lake properties. Finally, we carried out several drone-based surveys using a thermal camera to record spatially distributed lake temperatures. As well as discussing our monitoring network, we also present data that reveals Greenlandic lake evolution at a resolution not previously seen, showcasing an observational framework that could be replicated at other lake-terminating sites elsewhere in the world.