Tuesday :: Dec 18, 2007

season's end


by Christina Hulbe

30 November
As I start this post, I'm sitting in the cook tent at our Kamb Ice Stream camp (82.84 S, 154.74 W). We've been in the field for two weeks and everything is going well. The radar systems (three, two at 2MHz and one at 100 MHz) are all working well and the GPS surveying is going quickly. In two days we will move to our next camp, at the outlet of Whillans Ice Stream. We have about two more weeks left to go.

note: Back in late October, I wrote about upcoming field work in Antarctica (here and here). I started this post while in the field but am back at McMurdo Station on Ross Island now.

time flies
The days all have a rhythm that settles into place as soon as we are out on our own, away from the frontier town that is Mc Murdo Station.

* Each morning we have a radio or satellite phone check-in with "Mac Ops," the McMurdo radio base (5 people in camp, all is well). Our check in time is 8 am. If they don't hear from us within a few hours, a search and rescue operation is put into motion.

* Whomever is first into the cook tent starts heating water on the Coleman stove for breakfast, coffee (press pot with Portland's own Stumptown), thermoses for the day out in the field, and to keep the supply up in our cooler.

* As breakfast proceeds, we finalize the work plan for the day and make lunches.

* Dressed in layers according to the weather, field parties (usually two) set off on snowmobiles for the day. We carry food, extra clothes, survival gear, and perhaps crevasse rescue gear, in addition to science equipment.

* Field group check in (via satellite phone) is scheduled at 6 pm each day, earlier if a team is working in a potentially dangerous area. We evaluate progress and estimate time back at camp during the check-in.

* Whomever gets back to camp first usually starts cooking dinner. Tonight we had pizza cooked in a little Coleman oven. Really. Life is good out here.

* The day's data are processed and discussed while dinner is cooked. The conversation continues after dinner as dishes are washed, and plans are made or adjusted in light of the day's observations.

* We're off to tents and sleep by 10:30 or 11 pm.

There are no "days off," we just work until the work is done. We can work in most weather, though we did lose a couple of days this year to 30+ knot winds with visibility of 10 meters or so due to blowing snow.

progress
The season has gone well so far. We've made some observations that confirm our ideas about past variability in the position of the Kamb grounding line.

We've also taken the opportunity to add some observations of features I never would have known about had I not been working here last year. The kilometer-wide zone where the grounded ice sheet goes afloat to become the ice shelf is marked by long, narrow fractures that are generated as the transition ice bends with the tide. Last year I spent some time sitting at the grounding line, listening to the fractures propagating below me (a sort of deep, echoing pop). This year we brought some geophones to listen to the propagation events in a quantitative way and we're mapping the surface expression of the fractures so we can do a proper geomechanical interpretation.

The cracks are narrow at the surface, a centimeter or less across, but we didn't know what they looked like below the upper 10 centimeters or so (wider?). This year, our mountaineer and I set up an anchor on the surface, donned climbing gear, and dug a pit over one of the cracks. Indeed, they do widen with depth, at least for the upper 3 meters or so. Beautiful blue down there, with ice crystals, small hexagonal plates, mostly, growing out into the void between the walls. I could spend hours marveling at all these little jewels.

14 December
We are back where we started our field work, at Siple Dome camp (81.39 S, 149.04 W), on our way to McMurdo and from there to home. Our farthest-south camp was at about 84.5 degrees south latitude, about 30 kilometers from the Transantarctic Mountains. Siple Dome is a slow-flowing ridge between two ice streams that was the site of an ice core drilling project in the mid-1990's. The camp is now maintained in modest fashion as a waystation for work in the interior of west Antarctica. We arrived here late yesterday and spent time today packing cargo and organizing it onto pallets for transport back to McMurdo. We fly by Twin Otter tomorrow but our cargo will go by C-130 a few days later (we hope).

The season finished well, plenty of interesting observations and my collaborator and I even managed to fit in a day trip to Crary Ice Rise, a place we both wanted to visit but had to abandon last year for lack of time. The slow-flowing ice rise forms where the Ross Ice Shelf has run aground on a relatively shallow patch of the sea floor. The ice rise is an important feature in the region, playing a role in directing the discharge of ice from the ice sheet and into the ice shelf. Fantastic snowmobile-gobbling crevasses surrounded the area where we worked.

17 December
We've been in McMurdo since about 11 am on the 15th. Our cargo is still at Siple Dome (C-130 flight cancelled today due to fog at that location). This means we have relatively little to do other than office work, though there are some nice hikes around town. At this point though we just want to be on our way north and home.

19 December
Our cargo flight was delayed due to weather but finally arrived at Williams Field (a temporary airstrip on the Ross Ice Shelf) yesterday afternoon and made it up to town at 10 pm. This morning we set our boxes of science equipment up for shipping back to the U.S. (via an actual ship) and returned our camping gear and so on to the various departments that maintain it. Tomorrow, if all goes well, we fly north on a C-17 to Christchurch, NZ.

Christina Hulbe :: 6:30 PM :: Comments (7) :: Digg It!