Hunting supraglacial lake drainages to survey englacial channels – an airborne survey with Polar 5
In July and August 2021, Angelika Humbert and Veit Helm conducted an airborne campaign in northeast Greenland with Polar 5. Angelika Humbert, Professor for Glaciology at the Alfred Wegener Institut and co-lead of subproject 2, reports on their measurements from the air - searching for supraglacial lakes that suddenly drain.
October 14, 2021
What did you aim to measure during the airborne campaign?
We were aiming at surveying the pathways of water through the glacier when supraglacial lakes are draining. While we can detect supraglacial lake drainages relatively well from space, we do not know much about how this drainage is actually happening. While it is likely that massive fractures are forming that allow the water to drain in only few hours, we are still puzzled how the subglacial system can accommodate such vast amounts of water. And the oceanographers in GROCE2 are eagerly waiting to know where that freshwater is discharged into the ocean, how much and of course when – all really tricky questions!
Which measurement methods did you use? What was your approach?
Radio echo sounding can help here to detect features within the glacier, like we expect them to be formed during a drainage and remain intact for some time. While we detected more or less by chance in former airborne campaigns features in radargrams that we interpret as former englacial channels, we dedicated this airborne campaign to detect them right after drainage. To this end, end of July and early August was the perfect time for this campaign.
How were your working conditions?
We were really lucky with the weather in the beginning and right after arriving with Polar 5 at Station Nord / Villum Station on July 27th, we conducted the first survey flights right from the next day on. But as Station Nord is well known to be a challenging place in terms of weather, the last two survey flights required some patient waiting for flight conditions. In the end, we were got even more than we planned for – special thanks to a phantastic crew, chief pilot Dean Emberley, co-pilot Marc-Andre Verner, the AirMech’s Luke Cirtwill and Ryan Schrader.
Which thoughts did you have when flying over the supraglacial lakes?
After years of studying supraglacial lakes with satellite remote sensing, the flight campaign in the middle of the melt season was very impressive – a bit as if all ‘data’ is becoming alive. These lakes are so incredible large when flying over them and when they are located in the crevasse zone it is amazing how their lake ground looks like. As fascinating they are, they are also a sign for deteriorating conditions for healthy glaciers.