May 26, 2023

Celebrating 2500 m depth - again

Five nationalities of drillers and associates celebrating 2500 m drilled core: Grant, Søren, Yannick, Barbara and Bhikaji.

Yesterday, 2500 m logging depth was celebrated in camp. Then today, 2500 m drilling depth was celebrated. The logging depth and the drilling depth differ by more than 10 m, because they have different zero points and because they are measured differently. Logger’s depth is relative to the surface of the ice sheet (the year the drilling was initiated), and it is obtained by adding up the length of all the drilled ice cores, after they have been fitted carefully together. Driller’s depth is relative to the drill position when it is ‘at surface’ (meaning it is at its uppermost position in the submerged drill trench) and it is measured in terms of cable length that is spooled into the borehole. Whereas the logged depth is the ‘official’ ice core depth that will be applied for all of the measured ice core records, drillers depth is an important internal number to keep track of for drilling and logging. And by having two independent depth measurements it is possible to check for consistency. Just to complicate matters, we also have a third depth unit which is the ‘bag’. For packing and shipment out of camp, the ice cores are cut into 55 cm long sections, that are named ‘bags’. Bag 1 is from surface to 0.55 m depth, bag 2 is from 0.55m to 1.10 m depth etc. The bag unit allows for yet another series of celebrations as they have round numbers out of phase with those of depth. E.g., the other day, the science trench could celebrate the processing of bag 4500 (2475.0 m logged depth). Celebrations are important to keep the good spirit when the ice cores tend to look pretty much the same week after week.

What we did today:

1. Four ice cores drilled today.
2. Logging depth: 2516.64 m. Processing depth: 2510.20 m.
3. Physical properties analysis depth: 2500.30 m.
4. Continued beam grooming skiway. Drift dunes are hard to get rid of.
5. Tested camp sirens at 7 am. Could be heard in all sleeping facilities in camp.
6. Furnishing living room outside main Dome in the hope that summer will arrive.

Weather today: Blue sky all day. Temperatures -18°C to -31°C. Westerly wind 6-14 kt.

FL, Anders Svensson

Two more drillers on the other drill shift: Josie and Kenji.