09-07-05: Stop and think – Ice observation |
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09-07-05: Stop and think – Ice observation |
Ute_Kaden |
Sep 9 2005, 09:20 PM
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TREC Teacher Group: TREC Team Posts: 203 Joined: 27-April 05 Member No.: 10 |
Stop and think – Ice observation
9-7-05 2005/09/07 21:51:01 UTC Longitude: 153 30.503 E Latitude: 87 4 N Fog, Sun, Blizzard Greenland low pressure system Air: -9 C Water: -1.7 C 30- 40 knots wind Satellite image of the low pressure system Weather changes fast in the Arctic. We were standing on the bridge between 11 pm and 2 am during night and observed a weather change from deep blue, sunny sky to blizzard like conditions with zero visibility. The main weather player was a Greenland low pressure system clearly visible on the satellite photo. The barometer read 994 mbar. Heavy ice conditions made traveling towards North very difficult for the Healy and the Oden. Backing and Ramming by the Healy over night , no distance gain toward north and traveling in Blizzard like conditions made the two ships stop to assess the situation and figure out a plan how to proceed. A look at the different maps shows our travel pattern dictated by the heavy ice cover and the zig-zag pattern of backing and ramming by the Healy. During our stop we are drifting South with the ice at about 1 knot. Track 9-6 to 9-7, Going nowhere Healy slides on the thick ice and needs to back and ram to go forward Weather changes fast from sun to snow Afternoon and we are moving again! The Oden Helicopter was able to fly an ice reconnaissance flight and with the help of satellite photos a new course through the ice was found that brings us to planned science stations and north. I went on deck with Dr. Thomas Grenfell (University Washington) and Jeremy Harbeck from the ice program to help with data collection. They study the “Energy and mass balance of sea ice” and used a Heiman KT – 19 apparatus that reads thermal infrared radiation and interprets it as temperature. By pointing the instrument toward ice, snow and open water the sensor translates the emitted wavelengths into a temperature reading. The theory behind it is Black Body radiation. A black body radiates its energy in different wavelength that corresponds to the blackbodies temperature. The temperature of stars is determined in a similar way (blue stars are very hot, orange ones are cooler). Jeremy Harbeck takes field notes Dr. Grenfell with the K-19 meassuring thermal radiation Surface temperatures of the ice, meltponds and sea water are good indicators for the net energy balance of the sea ice. With this information scientists are able to predict the unset of melt and the unset of freeze of the Arctic sea ice cover and to study heat and mass balance of the ice and the resulting annual cycle of grow and decay of the ice. Sea ice next to the Healy Best Regards, Ute Kaden |
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