Edge of the Arctic Shelf
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Daily Update

Dispatch 16 - September 25, 2003
By C. A. Linder

Weather conditions: Overcast skies, calm winds and seas, air temperature 28°F

Long line
A mooring is hauled in by its orange top buoy.
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Mooring Marathon
I don't think I have ever seen Bob Pickart happier. The WHOI mooring crew brought four more moorings safely on deck today, taking advantage of the ice-free, calm open water. To top it off, all of the instruments that we have downloaded data from so far were carrying a full load of 14 months of oceanographic data! There is always an element of risk with moorings. The ocean is a very hostile environment - moorings can become dislodged and drift away, they can fail to release, or the instruments can just simply not work. The entire science crew is ecstatic - data of this kind has never before been collected in the Arctic Ocean. What's so special about this mooring data? The spacing of the instruments, in the form of a picket fence across the shelfbreak, allows us to see a cross-section of the temperature, salinity, and currents of this part of the Beaufort Sea over the entire year. Sarah Zimmermann worked for 20 hours straight yesterday checking over the moored profiler CTD data. Dan Torres has been working nonstop today extracting the current data from the moored ADCPs. I asked Bob how long it would take to analyze all of this data. He replied: "at least five years."

Ryan Schrawder pauses during a mooring recovery.
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I have received several questions from Mrs. Werner's 6th grade class at the Morse Pond School.

Question: How thick is some of the ice on this trip compared with last year?
Answer: Last year the ice was dense, but broken into small chunks. This condition is known as "brash ice." Check out this photo of John Kemp and Dan Torres deploying a WHOI mooring last year. This year, we haven't seen a single chunk of ice since our CTD work in the northern Chukchi Sea. This is mostly a function of the time of year. Last year's deployment cruise on the Polar Star took place in July and August. At that point, the ice in the Chukchi Sea and southern Beaufort Sea was melting and breaking up, but hadn't completely melted away. This September, the annual ice has melted back as far as it will go... It's only a matter of time before new annual ice starts forming, since this process begins in October. The ice edge creeps back, slowly covering the Western Arctic with a layer of new annual ice. Earlier in the cruise, when we did see ice, it was similar to what we encountered last year - broken chunks floating in loose congregations. We have done very little ice breaking this year - mostly just "ice pushing!"

Question: What has been the most interesting finding on this trip so far?
Answer: WHOI Principal Investigator Bob Pickart is elated by the performance of his moored instruments. This quote helps put it in perspective: "We have just looked at the data from one of the coastal moored profilers. This one instrument performed four CTD casts per day for 14 months... That's 1,600 CTD casts! In comparison, here we are on the Healy on CTD cast number 121."

This question comes from David, who's in 4th grade at the Mullen Hall School in Falmouth, Massachusetts.

Question: If the wind was heading north through the eastern hemisphere over the north pole into the western hemiphere, once it passed the north pole would it be heading southwest? P.S. If you are standing on the north pole, how do you describe the direction of the wind?
Answer: Hi David, good question! Winds are always named by the direction that they originate from. So, you would call that northbound wind a "southerly." As the wind crosses the pole, it automatically becomes a "northerly" since it is coming from the north. By that convention, if you're standing directly at the north pole, any wind you feel would be a "southerly" since the only direction you can go from the pole is south!

Ladder up
John Kemp climbs out of a storage hold deep in the bowels of the ship.
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Tonight the CTD watchstanders, led by CTD expert Marshall Swartz, will be testing the CTD sensors that will be redeployed on the moored profilers. Carin Ashjian will also do another net tow at 4AM, so we'll see if she finds some more copepods. Tomorrow we will recover the last two WHOI moorings and Lisa Munger's Acoustic Recording Package (ARP).

If you have a question about Arctic oceanography, shipboard life, or what we had for lunch on the Healy, send your question to arcticedge@whoi.edu. I'll do my best to find the answer and post it in a dispatch.

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