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Polar Radar for Ice Sheet Measurements

Curved ice line
Jagged line
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Day 21 - May 26 2006

Claude makes a final check of the depth sounder system before leaving camp to map.

The mapping is proceeding well. Today was the clearest day we have seen, giving us more fantastic views. The closeness of the horizon and the rapidly rising mountains in the distance, as we drive across the surface, drives home the awareness that we really are on an ice dome and not a flat ice sheet. The closeness of the horizon makes it feel a little like being on the moon. We completed 7 more lines today of the big grid. Dennis and I are about half done with the depth sounder mapping. We have completed 12 out of 22 lines of the 9 km x 9 km grid (not counting the 3 cross lines) and we have managed to process a file from today's run to sharpen the picture.

Our first preliminary look at processed data for a vertical profile of Flade Isblink from the radar depth sounder for a segment of one run. The vertical and horizontal scales are essentially arbitrary. The ice bedrock interface is delineated by the dark region near the bottom of the figure at about 611 meters depth.

The bottom is at about 611 m, very distinct but nearly flat and featureless. We are seeing structure in the ice, but not yet sure what it means. There is a thick dark layer at about 85 m that may be a surface effect and light layers above as well. The light layers could be melt layers that have refrozen, but since the depth sounder is designed for deep layers and has only 5 m resolution, we will have to wait until we deploy the accumulation radar to be sure. Just below the surface, at about 2 m, our group pulled out a chunk of ice that is more than 60 cm thick. We could have done another 2 lines or so but we had a little adventure. Dennis fell off the sled on a bump and because of limited visibility behind the radar box from the Skidoo, it was nearly another 4 km before I realized he was gone. There were some anxious moments when I turned around and went back for him, but fortunately he was unhurt, and ready to call it a day. Also, we had acquired a lot of data on the radar computer from the last several days and we were concerned about getting it saved. Everyone in camp had a good laugh about the sled incident when we returned and needless to say there was a lot of good-natured ribbing about it at dinner.

Flags demonstrating the multinational collaboration of the Flade Isblink project involving five countries. From right to left, the participating countries represented by their national flags are Denmark, Greenland, Iceland, Sweden and the US.


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