July 19, 2022

Hurry up and wait part 2

Located in the science trench, the famous ‘Swiss’ saw that makes two horisontal cuts of the ice core splitting it into three sections. According to the rumour, the same saw was used already for the Dye-3 deep core that was drilled in the early 1980’ies. Since then it has cut its way through the NGRIP, NEEM and EGRIP ice cores, so it has experienced the last glacial cycle a number of times.

Weather did not improve since yesterday; we woke up to another snow shower, fresh snow on the skiway and temperatures close to the melting point, so we decided to postpone the flights one more day. The drillers have filtered the borehole for ice chips that were left behind during drilling, so only one ice core was drilled. For this run the pump was mounted in the drill. In the science trench, a problem with the line scanner software was fixed and the first cores could be measured and packed. The line scanner is essentially making one long image of the entire ice core broken up into ca 1m long sections. Before the core is being ‘filmed’, it is cleaned carefully on both sides enabling any impurity, air bubble or structure in the ice to be identified. In the last glacial period, where the impurity content of the ice is relatively high, the annual layers of the ice can be seen by the naked eye. That is because the impurity content has a seasonal variation. In the about 50.000 yr old ice currently being processed in the science trench we thus see annual layers with a thickness of about 1.5 cm. Very few – if any – other paleo archive has a similar high temporal resolution at this age.

What we did today:

  1. Logger’s depth at 7 pm: 2204.72 m. Logged core: 6.10 m.
  2. The bolehole was filtered most of the day. The pump was mounted in the drill.
  3. Processing in Science trench. Last bag packed: 3865. Production: 4.95 m.
  4. Reorganizing cargo for the coming flights.
  5. Fixed a software issue with line scanner in science trench.
  6. Installed door for new entrance to the drill trench.
  7. Cleared entrances to trenches.
  8. Groomed skiway all day long with two Pistenbullies.

Weather today: The day started out with overcast and snowfall. In the late morning blue spells appeared and we saw the sun occasionally. At 11.30, the wind died and temperature readings became positive. However, as soon as the wind picked up again, the temperature dropped to -1.0°C, so most likely, the weather station heated up in the sun while it was windless. Nevertheless, it was a very warm day. In the evening, the clouds lifted and temperatures dropped to -11.0°C at 22:00. Wind: 0-8 kt from Northerly directions until 18:00 shifting to SW.

FL, Anders Svensson

Visible annual layering in the cleaned ice core slab prepared for line scan. 1.5 cm thick annual layers are seen by the naked eye. This core is a bit ‘relaxed’ as it has been stored at EGRIP for three years.

The ice core as seen by the line scanner. Black areas are transparent ice and white or milky layers have elevated levels of dust, calcium and other impurities. This core was drilled this season.