Wednesday, January 8, 2014

Another view on ABN

Sitting in the warmth of Hobart, I just came across a tweet of a satellite image from NASAs MODIS: taken on December 16 when we were labouring away in bad weather to get the camp established. The image clearly shows a large storm system over ABN and a swathe of East Antarctica.

Friday, January 3, 2014

ABN - The pictorial

So our stay at Casey continues - we were due to fly home today, but weather prevented our departure. We got up at 3am ready to drive to Wilkins aerodrome and were informed that we should go back to bed. Hopefullly tomorrow morning, Saturday, we will succeed.

The upside is that the extra time has given me the opportunity to assemble some pictures as promised, so I hope you enjoy putting images to the words of recent weeks. A few of these are larger versions of images you have seen. Images are free for non-commercial use.

Arrival at Casey by US C130 aircraft.

Full moon at Casey.

Williamson Glacier on eastern Law Dome (en route to Dumont d'Urville).

On approach to Dumont d'Urville skiway: view out to Dumont d'Urville  (island in centre).

Aerial view of Cape Prud'homme and traverse marshalling area on hillside above.

Another view of the traverse marshalling area.

DDU Station from the sea ice.

View back to Cape Prud'homme from DDU.

DDU resident: Emperor Penguin.

Cape Prud'homme.

Cape Prud'homme.
Map of the traverse, showing daily stops (15 days).

Traverse with tractor 5 (the one I drove) out front.

Towing a stuck tractor - view from the kassbohrer.

Traverse underway. The orange fuel tank holds 12000 litres of fuel.

Traverse in blizzard conditions.

Sun dogs around midnight.

The raid team on arrival at ABN.

First Basler flight, overflying the ABN skiway.

First Basler arrival.

Kitchen/living tent looking from kitchen (behind).
Firn air drilling tent.

Accommodation tents after snow.

Kitchen/living tent (looking toward kitchen)

Camp with sun halo.

Processing tent.
Main drill tent.

Shallow coring.

Main drill tent, showing excavated floor to accommodate drill tower.

Camp scene: L-R, Kitchen/living tent, processing tent, firn air tent (distance), main drill tent (corner only).

Camp scene.

Camp scene.

First half and full season team.

End of firn drilling - second pair of gloves worn out!

Aerial view on departure.

Tuesday, December 31, 2013

Happy New Year from...

... Casey Station!

Some explanation: I started yesterday (Monday) thinking I had another night at ABN, but following some firn air pumping late on Sunday night, the ice was starting to say clear things to us... there was little open pore-space left. The bubbles were largely closed, and at our next level, a metre or so deeper, Jerome and David were not able to extract much air despite pumping with maximum available pressure.

Knowing that this was the case, we looked again at the logistical picture. A flight was due on Monday afternoon to exchange six camp members, and the weather was showing some risk of preventing another flight until Friday. But Friday is also the day of our Airbus flight from Wilkins (the ice runway that serves Casey) to Hobart. This was not a risk we cared for, given that our science role at ABN was effectively over, so we put on our skates, packed our bags and made the Casey return flight.

It was a time of mixed feelings, saying goodbye to our friends remaining behind. For the three traverse team members, who had started this back in early November, this was the end of a long chapter -  Noel (diesel mechanic) and I were leaving, and Sharon remains as field leader. Having established the camp, there was a sense of wanting to see it to conclusion too, but our roles are complete; and the process of extracting people and infrastructure will be an imperative over the remaining weeks to late January when the last tent is pulled down and the remaining few come home. The departure marked another achievement too - we brought out over 600kg of ice core.

It was quite remarkable returning to the coast after more than a month on the high plateau. We were greeted by scenes of meltwater, positive air temperatures and soft, warm, moist air filled our nostrils. The coast is the home of life on this continent and you can see and smell that too - so striking after the barren, sharp cold of the interior. For sure, we saw a few birds far inland, but they were interlopers like we were: able to make the journey naturally, but aliens nonetheless. Of course we could only sustain our efforts with the aid of the fossil remains of past living things - distilled to the fuel that propelled our tractors and planes, powered our generators and heater. This strikes me as something of a circular situation - the past provides energy, for us to extract ice ... to explore the past.

So this brings to a close my personal journey to ABN and back. I will make one or two more posts to this blog, to put up some pictures now that I am back in the land of the internet, and probably to cap things off at the end of the whole project with some kind of summary of events. Watch on twitter (@tasvo) if you want to be reminded. But the story now belongs to the group remaining at ABN - there is the major portion of the main core yet to drill, and another auxiliary (~100m) core for the sulphur studies of our French partners at LGGE. You can follow events through the AAD website.

And a final comment - I've been surprised and pleased to hear of the many folk who've followed this blog... thanks for your interest. The knowledge that you were doing so was a factor in keeping me at the computer after midnight several times (that's a good thing!).

And a final picture from the Basler window as I left yesterday...

Sunday, December 29, 2013

December 29 ABN News

I awoke this morning after a late night chasing the drilling problem in the firn tent, and thought how well I was acclimatizing to the cold. Actually though, it wasn’t me acclimatizing to the weather: just some amazingly warm weather. Our maximum today was -1.5C in the shade. Drilling tent doors were open to try and keep them cool enough to work and the processing tent was not used. Some outdoor shallow coring was done instead, and even this required some care and shading to keep the ice from melting in the sun.

We tried a few things with the firn drilling in order to get it to retrieve core, initially without success, but eventually a combination of things seemed to do the trick, and we were back in action. We had expected a long ‘lock in’ zone (as explained in an earlier post), but we are finding that the pores are closing very fast (with increasing depth) and it is proving difficult to get large air volumes. This is disappointing for the firn air science, as it won't provide as extensive a record as we had hoped. There is a bright side, however as understanding the unexpected properties of this site and the way the snow turns to firn and then ice will be useful in the broader interpretation of ice core results. Such unknowns are part of the territory of course with research.

Tomorrow six of the first half team change out from camp, and six second halfers arrive. Those of us in the firn air team will spend a bit of time hunting for the last dregs of air at depth, and pack up for a return to Casey the day after. It will be a strange feeling to end my personal ABN chapter after nearly two months. Still, I am jumping the gun â€" there will be more to report in the next couple of days, and that is without even considering what the weather might do to plans.

Saturday 28 December

Today started with one of those special Antarctic moments… I extruded myself through the tent tunnel to find almost clear skies and perfectly still conditions. There was a thin misty feel, a little like an early morning in winter and the sun was accompanied by a magnificent ring/rainbow.

The misty conditions quickly lifted and it has become a warm, bright sunny Saturday. Just after breakfast it was almost like a Saturday morning in suburbia, but the “lawnmower” sound was doctor Malcolm using the snow-blower to excavate a trench to take our ice core boxes: very timely given the warm conditions, as we need to get them out of the sun.

One of the Hobart scientists, Andrew, has got a laser spectrometer up and running and is measuring our first ice samples (for those interested, this device measures isotopes of oxygen and hydrogen in the water/ice, which can be interpreted as past temperatures). We are interested to see seasonal variations in the ice, especially in the shallow sections near the surface, as these will tell us more about the annual snowfall rate here.

The main core drilling continues, at 114 metres, and the team have been working hard to solve some technical problems with the drill. The firn air coring has now reached 102 metres and we are in the special zone called the ‘lock-in’ zone, where the ice is still porous enough to allow us to pump trapped air out, but the air itself is now isolated from the modern atmosphere. The point of this is that we can get very large samples of air that is decades old: much larger that can be obtained from bubbles in a relatively small ice core. Such large samples can be used to measure exotic gases like carbon-14 methane.

Others have been busy making use of the good weather to drill a shallow core. This is important because the setup of the big drills makes it difficult to get a nice undisturbed ice core from the surface, which gets trampled and cut away. The shallow core will be about 20-30m deep and the measurements on this core will overlap the other ice cores and allow the continuous record to be assembled.

The changeover of staff between the two half seasons is getting closer. We could be flying out as early as Tuesday, so we are working hard to complete the firn core and air extractions and leaving time to pack up. The actual pumping takes a couple of hours, filling flasks as well as making online measurements. We are looking at the depth remaining (which is sort of unknown, but we estimate to be another 10 metres or so) and figuring out how many extractions we can fit in the time left; the more the better!

Postscript: Midnight
How quickly things change â€" the firn air coring has hit a nasty snag. The drill stopped feeding near 103 m and after a lot of diagnosis we think the problem is the buildup of fine snowy dust in the bottom of the hole â€" accumulated from the drill runs abrading the hole, and probably from the insertion and removal of the long bladder that is used to seal the hole during air extraction. Whatever the exact cause, the drill is not successfully getting a bite on the ice and so our progress is halted. We have a few ideas to try tomorrow, and Trevor, one of the drilling experts in camp says he has seen this problem before and that a solution can generally be found. While this turn of events makes for some suspense/intrigue for readers, I must say I’d prefer a more boring blog at this point!

Friday, December 27, 2013

27 December Update

The ABN camp is really in full swing now. Everyone is busy at their tasks: two drilling teams, a processing team, and support folk. The processing team consists of a number of the most recent arrivals, and they have put up the last of the large tents and are filling it with core cutting and cleaning facilities.

Yesterday, in the evening, we enjoyed our Christmas celebration. A delicious meal and everyone swapping stories, including anecdotes from the countless accumulated field trips. These included fond memories of some of the pioneers in our field, notably our recently departed Danish colleague Sigfus Johnsen, whose memory we toasted.

The weather hasn't been so good the last couple of days, with a fair bit of wind and snow, as I think I mentioned. We are largely immune to the weather now, with all tents up and most work inside, but moving around camp with the cloudy skies and 'flat' light can be tricky. There are 30cm plus high drifts between the tents that weren't there a day ago, and these nearly invisible obstacles make for some clumsy stumbles. I'm nearly at the point of having to get a shovel to dig out the entrance to my tent - entry is now a hands-and-knees slide down through the canvas tunnel; exit is a case of throwing out whatever you are carrying and diving uphill onto the snowdrift.

The drilling continues well - the main core has reached 100m, and the day has a couple of hours left. The firn air coring is also going well - we are at 85m and Jerome and David have just completed another air extraction, with air that looks like it is about 13 years old, and still in the porous phase (the bubbles are not sealed and the air is still actively connected to the atmosphere).

I need to finish off now and go and drill a few more metres in preparation for the next air extraction.

Thursday, December 26, 2013

ABN December 25

Today brought some more developments at ABN. A Basler flight brought in our last three science crew and our changeover mechanic, who was scheduled in January, but will have the opportunity to get a handover of the setup from the current mechanic. The notable thing about this was that Bloo, the new mechanic, arrived in Santa costume, which combined with his impressive beard and jolly deameanour had a very authentic effect - at least if you ignore the fact that the costume was probably a couple of sizes too small and back-to-front!

Work continued with some success. The firn-air team and the main coring team have now each drilled to a little over 50 metres. The progress of the firn air coring was stymied for a while by ongoing trouble with tension in the spring "skates" that prevent it from spinning in the hole rather than drilling. For a while around the middle of the day we were stuck around 35m depth, where the skates had slipped in the hole, over-enlarging it and threatening any ability to progress. With some good advice and head scratching these difficulties seem to have been solved, and we hope to pick up the pace tomorrow.

The newcomers from yesterday have thrown themselves into their work - one team putting up the final large tent which will house core processing, and others organising the kitchen and living area to cope with the large population: now 19!

I've included a picture that shows the camp this evening - it is rather windy and snow is drifing through the area providing an atmospheric effect. It isn't as cold as it has been (only -23C) but the wind makes it rather uncomfortable.

As I said yesterday, our Christmas will be tomorrow, a shortened work day and a special dinner at the end. I think the best present for us all will be a day of good progress.