31 May 2010

Big brother is watching

The relative composition of the isotopes Hydrogen and Deuterium (red) and Oxygen-16 and Oxygen-18 (blue)
A historical plot in ice core science. The curve shows the relative composition of the
isotopes Hydrogen and Deuterium (red) and Oxygen-16 and Oxygen-18 (blue) in the
melt water from the CFA system. The high values to the left are from ice from our
present climate, while the lower values to the right are from ice from the end of last
glacial period. This is the first time ever that the termination of the glacial period is
in isotopic ratios in the field and on-line. All thanks to modern laser technology.

Christian has made an in camp information system. On electronic bulletin boards in the kitchen and in the lounge we can now see current weather, some small world news,
follow on-line a readout from the drillers cabin on progress of drilling, and new bulletins
from camp on flights, power downs, dinner times and other news. In the lounge, drillers off duty loudly comment the progress of drilling of the other crew: "Oh, I think he's lost it" or "He's got ice on his shoes. He's bound to stop and pull back soon". A little thing like this adds some flavour to camp.

What we have done today:
1. Drilling, filtering hole and logging.
2. Taking down gray welding tent. Moving last fuel tank to Apron.
3. Processing brittle ice cores. Processed 33 bags, from 2169 to 2201.
4. Grooming Apron, taxiway and part skiway with tiller.
5. Measuring CFA. Today we measured 20.9 m. Last bag 2585, 1421.75 m.
6. Measuring CFA on brittle ice on 6 bags (3.3 m).

Ad.1: Drillers report:
Unstable drilling continues since mounting the new cutters. Long cores can be produced
but these runs leave behind too many chips sabotaging the next runs. We mounted
Pressure Tube "1" again to test whether we could get more power from it at the 12 A
limit. Now as we approach and exceed 12 A the motor RPMs stay near the nominal of
80 rpm.
We filtered the borehole before making this change. Nonetheless, three runs with this
pressure tube were hampered by high current after 60 to 90 cm of drilling and runs were stopped. Tomorrow we will mount the old cutters and return the drill once again to the configuration used at the end of the 2009 season, with an open hallow shaft, lower
valve and a cutting pitch of about 2.1 - 2.4 mm.

Today we produced 9 meters of ice core.

Drillers depth: 1884.50 m. Logging depth: 1900.69 m.

Ad.3: During processing today, several errors in ice core logging from last year were discovered. Some bags were cut at either 45 cm or 65 cm lengths and the bag marks
were put at the cuts. However, due to our system of double ice core length measurement using two different independent depth calculations, we have redundancy
and the total ice core depth is not affected. It turned out, that these errors were made
on July 20, 2009 where the loggers worked 24 hours to catch up with the drillers.

Ad.5: Today the CFA team passed into ice from the last glacial period, 11713 years ago. Many parameters showed variations, but several parameters do not show the
same degree of variations as at NGRIP or other Greenlandic sites previously studied.
Something makes NEEM a bit special, which is scientifically quite fascinating.

Ad.6: There has been some nervousness about the applicability of CFA to the much
fractured brittle ice. Last night the CFA group analysed 3 bags of ice with poor quality
and three with better quality. In the worst case some 10 to 15 cm from a 55 cm bag
could be measured, in the best case about 45 cm. It was concluded, that CFA is feasible
even in brittle ice.

Weather: Blue sky. -28°C to -13°C, 8 knots from SSE. Visibility: Unrestricted.

FL, J.P. Steffensen

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