Incredible news! Stay safe and look forward to news from way down South.
Posted by mainsailset at October 29, 2007 01:04 PMThanks for the news and best of luck to you. Enjoy the quiet, the absence of clueless humanity and and the privilege of being in such an out of the way corner of our earth, where few have been--to say the least.
As everything frozen on earth is now melting, the study of the ice becomes supremely important.
Posted by euzoius at October 29, 2007 01:18 PMprivilege
Indeed. I feel fortunate to work in a field (the research, teaching, and mentoring students) that is interesting, challenging, and important.
Posted by Christina at October 29, 2007 01:26 PMYou dont need anybody to carry your bags, do you? I would be more than happy to carry them around as long as i get to see antarctica.. :)
Posted by Greup at October 29, 2007 01:32 PMStay safe Christina.
Will you spend any nights on the "ice sheet"?
Posted by Seven of Six at October 29, 2007 02:00 PMWill you spend any nights on the "ice sheet"?
Almost all of them. We spend a few days in McMurdo on the way in & out of the field, working with cargo & camping gear, doing safety refreshers and whatnot, but most of our time will be spent in the "deep field," living in tents and working on the snow. We have an HF radio and a satellite phone for daily check-ins with McMurdo but other than that, we are on our own. It's a marvel. I'll try to post some photographs later this week.
Posted by Christina at October 29, 2007 02:20 PMYay pictures! Good for you, Christina! Thanks for all you do!
Posted by iamcoyote at October 29, 2007 02:33 PMthanks for sharing your blog Christina. It will be great to be following you from afar. Take care because we want you back safe in Portland!
Posted by Candyce at October 29, 2007 04:01 PMWhat a wonderful adventure, Christina. I will think of you on those frozen plains and hope to hear back from you soon of all you've observed. Stay safe and as warm as one can be down under.
BTW: This was a truly exceptional blog post. Thank you so much.
Posted by Mary at October 31, 2007 01:42 AMCan someone direct me to some available info on rates of vertical moulin penetration through sea or shelf ice? I find what look like useful abstracts but can't get to the articles on the web -- not in the right cliques.
Temp. range near zero, low salinity, related to shear fractures would be good.
Thanks,
Jay
Posted by jaynicks at October 31, 2007 08:22 AMJay,
Your question touches on a vairety of issues and I'm not clear on the connection you want among them so let's start simple and go from there.
Sea ice is ice that freezes at the surface of the ocean (more about Arctic sea ice here). An ice shelf is floating ice of terrestrial origin that forms where an outlet glaicer or ice sheet flows down to the coast and goes afloat.
A moulin, from the French, is a conduit through which surface meltwater flows down through glacier ice. The water may flow down to the base of the glacier (or ice sheet) or may join the englacial hydrologic system. The rate at which water flows through a moulin depends on the volume of water available at the surface. If the water flow rate is not fast enough to keep the conduit open, it will freeze closed.
At the large end of the spectrum is catastrophic drainage of the large surface melt ponds in the ablation (net surface melting) zone of the Greenland Ice Sheet. A friend of mine who works in Greenland told me that one large lake his group was observing drained in less than 2 hours at a volume rate that exceeded the flow over Niagra Falls. It's not very easy to observe these large features though (a flow rate like that is likely to destroy an monitoring equipment you might deploy). In any case, these are outliers at the large end of the spectrum. Here is a NASA news story about such work.
You might want to look for studies where glacier surface stream flows have been measured to develop a sense of scale for the volume of water involved in more typical situations.
Posted by Christina at October 31, 2007 11:01 AMHi,
I was hoping to attract someone not on the ice or nearly there. I'll happily take your lead but I figure you are rather busy at the moment.
The differences in berg size for the Larsen B event vs B-15 suggest a non-trivial model for ice shelf decay. The differences may have been satisfactorily explained & I just missed the articles.
I was wondering if I could construct a model of sheet decay. I have some relevant background & experience (ante-diluvian: on IBM /360s, PDP 11s) & webbed up (somewhat) on moulins, grounding zones, flow rates & deformations, . . . I know my ideas are probably (p ~= 1) naive and so I thought to read up on current models and their bases. After some serendipitous Google finds, some lacunae, am running into some blocks.
Likely a waste of your time (p < 1). Even if not I'm comfortable with March or whenever may be a better time.
Thanks for the pics in your Post 2.
Good luck in the field. Best of luck!
J
Posted by jaynicks at November 1, 2007 11:44 AMpapers about ice shelf collapse:
Scambos, Ted A., C. Hulbe, M. Fahnestock, and J. Bohlander. 2000. The link between climate warming and break-up of ice shelves in the Antarctic Peninsula. Journal of Glaciology. 46(154):516-530.
Shepherd, A., Duncan Wingham, Tony Payne, and Pedro Skvarca, Larsen Ice Shelf has Progressively Thinned, Science, October 31st, 2003
Vaughan, D. G. & Doake, C. S. M. Recent atmospheric warming and retreat of ice shelves on the Antarctic Peninsula. Nature 379, 328-331 (1996)
Note that the ice shelf collapses are catastrophic events under specific circumstances. There are reasons to speculate about rapid retreat of marine ice sheets but they are distinct from the ice shelf collapse issues. There are some straight-up papers about the physics that goes into the models too, look for textbooks by Van der Veen, Hooke, or Hutter, there is a review paper by Hulbe & Payne in, I think, 2001.
Posted by Christina at November 1, 2007 05:55 PM