Our work with the British Antarctic Survey

2017/01/19

Wednesday 18th and Thursday 19th January – level survey of module legs, soffits and skis

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DSCN2713 all modules at VIa

Up at 10am for line and levelling the B2 module. We will need to do the full level survey tomorrow.

At the situation report today I was advised that my flight out will be on the 1st February subject to weather.  Last out will be at the start of March.

Thursday 19th January

I was just about up and ready for the 8am start. The over-night moves, six day weeks, eleven hour days and communal living do play a toll on your energy levels – however others seem to be suffering more than me.

First thing this morning I did the full level survey of all the module legs, soffits and skis. Standing in front of the dumpy level doing very precise movements to sight the instrument and record the information meant my fingers were freezing within 30 minutes.  Halfway through I stopped to get my circulation moving and found this was initially more painful than the cold.

I logged the information and waited for information on the leg extensions from the HMI hydraulic control units which required the power and communication links to be established. After getting the required information after lunch I worked to ensure we achieved the leg extensions within the 1275mm to 1375mm range and minimised the number of legs between modules B2 to E1 that we needed to adjust. I came up with a strategy of stepping some of the modules soffits by 25mm within their length.

I also looked at an upper bound scenario where up to 60mm melt settlement affects some of the newly re-located modules but not others where the skis have already melted fully in. So this may mean that if there are a few sunny days that the levels we achieve in the next day or two will need the legs extending further to maintain a level soffit.  Having assessed this I am happy we could do minor adjustments in the module levels and still maintain the leg extensions within the set range.

Jan the glaciologist presented information about the Brunt Ice Shelf formation, features and growth. This included the recent growth of Chasm 1 which had been dormant for some years, but particularly the Halloween crack as it was named since its discovery in October 2016. The glacial models can show a range of scenarios, however there is considerable unpredictability at this point.

 

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