Tuesday, July 19, 2016
Another beautiful morning at EGRIP.
Today, Trevor Popp (Associate Professor at the University of Copenhagen) gave us a more in-depth lecture on the mechanics of ice core drilling.
The ice core drill is placed above the pit and is lowered by a cabling system. Its movements are controlled through instruments located next to the cable. The first drilling proceeds until the drill reaches 300-400 meters below the surface, which will take approximately 3-4 weeks. Each ice core extraction measures 3.5 meters long with a diameter of 10.16 cm. When the drill reaches 300 feet, the pressure of the ice will cause the hole to deform. Estisol-140 will be poured into the drill hole to prevent it from closing, and the drill will be lowered into the filled hole until it reaches the bedrock, 2550 meters below.
It will take three to four field seasons (summers) to reach the bedrock and 2 hours to extract the final ice core.
All of the ice cores are labeled and placed in a cold auxiliary room for storage until they can be shipped to Copenhagen for further analysis.
We all proceeded to the drill pit where we would witness the first ice core being drilled at EGRIP. Shots of Cognac were passed and we all toasted this initial drilling!
After lunch, Dorthe gave us a lecture on the Greenland ice sheet.
The largest ice stream in Greenland, the North-East Greenland Ice Stream (NEGIS), begins at the central divide and cuts through the ice sheet in a wedge shape. It divides into 3 smaller streams that empty into the Nordic Sea. Through radar detection, EGRIP was able to locate its camp directly above NEGIS.
The East Greenland Ice Core Project’s goal is to gain new information on ice stream dynamics in order to understand how ice streams will contribute to future sea-level change.
Ice streams discharge icebergs into the ocean, which accounts for one half of the mass lost from Greenland’s ice sheet. These streams are formed by the melt at the base of the ice sheet and reach velocities of 100 meters/year at 200 kilometers from the divide. They have doubled their velocity during the past decade.
Today, the NEGIS flows at 60 meters/year. Will there be a change in velocity when this project terminates in four years?
We anxiously await the results of Dorthe’s research.
Credit: Kristian Kjellerup Kjeldsen, Natural History Museum of Denmark
NASA scientists use satellite imagery that illustrates the movement of the ice streams from the interior toward the outlet glaciers. The NEGIS flow is illustrated above. The blue and purple are the fastest moving ice, and the yellow and pink are the slowest.
A decade of melt in Greenland’s ice sheet
Gathering in the Dome for a delicious dinner with peach cobbler for dessert and a few glasses of wine along with stimulating conversation was a great way to end this day.