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Polar Radar for Ice Sheet Measurements

Curved ice line
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Day 19 - May 24 2006

The days just keep getting better. This morning when I awoke my tent felt warm. I checked the thermometer I had attached to my coat zipper and it said 50 F. After having adapted to 10 F weather with -20 F wind chills, and crawling out of a heavy sleeping bag wearing expedition weight polyester thermal underwear, this felt almost tropical. The snow I had tracked in on the floor by the door had melted. When I stepped outside, I could see mountains off on a distant horizon that I had never seen before. It was a beautiful, clear, sunshiny morning. What's more, the winds were the lightest we had seen, and this was only the beginning of our best day yet at Flade Isblink. It was perfect weather for working outside on an ice dome. We all shed layers and struggled to avoid overheating.

The radar depth sounder mapping will follow this 9 km by 9 km grid oriented 49 degrees east of north. This orientation roughly parallels the Flade Isblink ridge

The Danish group and Bruce dug out the drill parts in long boxes, made a porch in front of the drill dome, moved the diesel generator back from the weatherport to its original and intended position, moved the 400-lb winch to the drill dome, excavated the tents that had been destroyed, finished the processing table for ice core segments when they come out of the ice, and fixed the Skidoo we will use for our radar mapping. Meanwhile, Dennis and I mounted the radar depth sounder box and radar antennas on the Nansen sled in preparation for our mapping. Last, but not least, we fired up the radar and the computer screen. To our great joy, we saw bedrock at the bottom of the ice dome at about 600 m (1800 ft) depth, almost exactly where we expected to find it based on airborne radar measurements over this area several years ago. Now, however, we will be able to see it in much finer detail So the depth sounder radar is working. It is ready to go and so are we. If the weather holds, tomorrow Dennis and I will start mapping a 9 km by 9 km (5.6 mile by 5.6 mile) grid centered on the drill site with grid spacing every one-half km (one-third mile). This grid will allow us to make a topographic map of the bedrock and map the deep internal layers of ash and sulfur laid down in some years by volcanic activity.

The radar depth sounder is housed inside the heated red box and strapped to a Nansen sled while pulled behind a Skidoo. Two log periodic antennas, one for transmitting and the other for receiving, are mounted on two-by-fours strapped to the box and aimed downward.

The weather was incredible this evening. The flags set up around camp to mark various points and supplies hung limp. There was not a puff of wind for the first time since we arrived. Bruce prepared a wonderful three-course meal of onion vegetable soup (to help improve our salt intake in these dry conditions), almond-lemon-chicken stir fry, and blackberry cobbler. It tasted so good that we all ate too much. Now we are sitting around the table after dinner flushed with our recent successes, hoping for more in the days to come, and fighting off sleep.

Claude and the Depth Sounder from the rear. The setup requires one person to drive the Skidoo and one person to sit on the small steel box on the sled and monitor a keyboard display while the system collects data. Foam insulation and an electric heater inside the red box helps maintain a proper operating temperature for the radar system. Note the limp hanging flags.


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