Big Ice

Greenland Lakes 2008

During the third season, Ian Joughin and Kristin Poinar from UW and Sarah Das and Mark Behn from WHOI returned to maintain the scientific instruments at the North and South lakes.

Chris Linder and Amy Nevala also accompanied the team as part of Live from the Poles, an NSF funded International Polar Year (IPY) outreach project. At the North Lake, the team placed dye into a melt stream flowing into a moulin, so that a second team could detect it emerging into a fjord 30-km downstream to determine the time it took the melt to flow beneath the ice. Unfortunately, they were unable to find the dye. While the team was there, the South Lake drained rapidly through a several-kilometer long crack, unlike the previous year when it had drained over the side. Fog limited visibility so all they could see was the water receding by a few hundred feet before it vanished, but they could hear loud cracks and booms as the ice fractured. All along the shoreline, the ice crackled with a sound much like that of milk being poured over a bowl of Rice Crispies, which likely was the sound of the ice straining as it was uplifted by several feet as the drainage rapidly injected water beneath the ice sheet. A small, unobserved, drainage also occurred at the lake just to the north of North Lake while the group was there. At both lakes the team was able to observe the crack immediately after the drainage and monitor the melt widening of the new moulins over the course of several days.


End of North Lake, Just Prior to Drainage
Hours after this image was taken from a helicopter flying over the lake, this lake drained to the base of the ice sheet in about 90 minutes. The linear feature extending from the middle left edge of the image into the lake appears to be part of the 3+km (1.8 mile) long crack that drained the lake the previous year and appears to have been active in the impending drainage.

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