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Polar Radar for Ice Sheet Measurements

Curved ice line
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Day 20 - May 25 2006

This morning dawned gray and breezy, but by midday it was sunny and still. I am struck by the changeability of the weather up here. In Kansas we like to joke that if you don't like the weather, wait a few minutes and it will change, but on Flade Isblink, this is literally true. At 2000 ft., in close proximity to the Arctic Ocean and with these low temperatures, it is close to 100% relative humidity all the time. This means that one minute the sun can be shining with clear blue skies and 15 minutes later there is thick fog with almost zero visibility, and then sunny and clear again 30 minutes later.

Pausing momentarily at a GPS waypoint while mapping the grid, Dennis adjusts our improvised sunscreen that cuts glare and allows us to read the computer screen.

We had intended to get an early start to map, but we had some problems setting up our satellite-based global positioning system (GPS) software. We use GPS to navigate across the near-featureless icecap and to constantly record our position on the radar images. The GPS has already proved critical for finding our way back to camp.

After we finally resolved the GPS issues, Dennis and I mapped the first five of our nineteen 9-km grid lines this afternoon and evening. We can tell from our radar signal that the bottom is very cold and smooth because we were constantly getting a strong return signal. In some parts of the Arctic and Antarctic, where it is warm and wet at the ice/bedrock interface, radar microwaves are absorbed (rather than reflected) and it is difficult to see the bottom.

A typical scene of the Flade Isblink ice dome and the tracks left by our skidoo and Nansen sled while mapping.

We found the surface to be extremely soft, and we had to be very careful each time we tried to accelerate from rest or our Skidoo would dig down into the snow rather than move forward. This was due to the drag created by the weight of the radar system (~ 250 lb) on the sled and two full grown men, plus extra fuel and gear. The trick is to accelerate very slowly with both of us off the Skidoo and sled. As soon as they started to move, we would jump on. On the other hand, the ride is extremely smooth.

As we were running our 4th gridline, the clear skies suddenly started to disappear and by the time we had finished our 5th line, we were in a deep fog with 100 ft visibility. Since it was also 9 pm by that time, we decided to call it a day and groped our way back to camp with the GPS. We did not see the tents and weatherport until we were practically on top of them. We put all of our faith in the GPS. Of course we also had an Iridium satellite phone and had left directions on our route with Lars as insurance in case our GPS had failed. We had a delicious meal of spaghetti and meat sauce that Simon had prepared and hoped for another good day tomorrow.


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