In continuation and expansion of the exploration of Greenland crevasses at Raven Camp, University of Maine graduate student Jessica Scheick and professor Dr. Gordon Hamilton returned to Kangerlussuaq, Greenland to continue investigating the cause of the cracks that appeared across the Raven Camp skiway in July 2012. Jessica sent this report from their recent field work.
The first portion of the work to be completed this season was the springtime installation and surveying of a new strain grid extending from Raven Camp downstream (approximately west) almost all the way to the ice sheet margin. Our research is supported by the National Science Foundation.
This grid extends about 150 km through potentially crevassed terrain, making snowmobile travel impractical. Consequently, we used a helicopter based in Kangerlussuaq for the work.
Initially we installed markers installed and then surveyed using global positioning system (GPS) receivers. We set up several stations to continuously record data throughout the melt season. These data will allow us to determine how flow speeds change throughout the summer melt season. They will also show if the extensional flow responsible for crevasse formation is migrating inland. Together with the strain grid at Raven camp, this information will provide a nice overall picture of ice flow in the region.
Although establishing the new strain grid was similar to the work done at Raven Camp last summer, we had to make a few additional considerations for sites installed closer to the margin.
Summer surface melting, faster flow speeds, and the higher potential for crevasses meant that markers needed to be anchored several meters below the surface. This required drilling holes 4 meters deep in some places. For the continuously recording sites that will operate throughout the summer, we mounted GPS receivers vertically on a plastic sleeve that will hopefully slide vertically down the marker poles as snowpack melts away.
What was supposed to be one springtime trip to Greenland ultimately turned into two after pilot illness and stormy weather made it impossible to complete the work during the first deployment.
I returned a couple of weeks later with fellow UMaine graduate student Liz Dengler to finish up the surveying and installations. At one station, we found two dead birds (believed to be a mating pair of northern wheatears); they’d presumably been knocked off course by the storms a few weeks earlier and had sought refuge against the GPS equipment.
In August, I’ll return to Greenland once again to collect the continuously recording GPS receivers left out this spring, resurvey the remaining markers installed in the new grid, and resurvey the markers installed last summer at Raven Camp.