Grounding Line Forensics: The History of Grounding Line retreat in the Kamb Ice Stream Outlet Region
Participants:
Ginny Catania,
University of Texas at Austin
Christina Hulbe, Portland
State University
With collaboration from:
Ken Cruikshank,
Portland State Univeristy
Funding agency: NSF Jun 07 - Jun 10
Project Goals:
Understanding ice streams is a long-standing objective of West Antarctic
glaciology. This field of study has progressed from recognizing ice streams'
unique geologic setting and associated dynamics; to concern over the rate
at which ice stream grounding lines retreat; to definition and location
of upstream onsets and the discovery of tributary networks feeding into
those onsets; and recently to the hotly debated possibility that the West
Antarctic ice streams might be grinding to an interglacial halt. Understanding
such processes has important influence over our ability to accurately predict
mass balance changes in this region. Currently, one of the five major West
Antarctic ice streams, Kamb, is quiescent, and another, Whillans, is slowing
in its downstream reaches. The Kamb shut-down appears to have begun at its
downstream end but beyond that simple observation, it is not possible, yet,
to draw meaningful comparisons between the two adjacent streams. We do not
know if current events on Whillans Ice Stream are similar to what transpired
during the Kamb shut-down. The work proposed here intends to bridge that
gap.
We will continue our previous efforts to identify and map ice surface and
internal features that chronicle the sequence of events leading to the Kamb
shut-down. In particular, we are interested in past grounding line migration
and the relationship between that process and ice stream shutdown. The Kamb
record, as we know it, indicates that the downstream reach is the first
to change, and this makes sense, for reasons discussed later in this proposal.
It is expected that this effort will yield useful insights into the influence
of grounding line dynamics on ice stream flow. The work will involve a combination
of field investigations using radio-echo sounding and GPS combined with
computational efforts involving the interpretation of ice-surface features
such as relict flow traces and crevasses.
Project Highlights:
We have finished all of our field work and are busily analysing and synthesizing
data. We found lots of interesting grounding line features including some
evidence that the Kamb Ice Stream grounding line has jumped in position
in the past. Joining us this last field season were the Polar-Palooza
team who are interested in highlighting polar research to the public in
the IPY.
Christina shot a mini-moivie
detailing the ins and outs of field science in Antarctica: GLF:
The Movie
We also have lots
of pictures
from our field seasons.
Published/Presented Results:
- G. Catania, T. Neumann, C. Hulbe and H. Conway, 2008 (invited) Understanding changes in the subglacial environment using internal layers, AGU, 89(53), Fall Meeting, Abstract C42A-04.
- C. Hulbe, G. Catania, O. Sergienko and M. Fahnestock, Stagnation of Kamb Ice Stream investigated using flow features within the ice and numerical models, 2008, IGS Symposium on Radioglaciology, Spain, June 2008.
- G. Catania, C. Hulbe, J. Greenbaum, Evidence of relict ice-shelf rifting and timing of grounding line retreat for Kamb Ice Stream, Antarctica 2008, IGS Symposium on Radioglaciology, Spain, June 2008.
- G. Catania, C. Hulbe, J. Greenbaum. Evidence of relict ice shelf rifts on the grounded ice of Kamb Ice Stream, Antarctica, 2008 NASA-PARCA meeting, Boulder CO, Feb. 2008.
- G. Catania, C. Hulbe, A modern analogy to relict grounding lines on Kamb Ice Stream, Antarctica, 14th Annual WAIS Workshop, Sterling VA, Sept. 2007.
