HR: 1340h
AN: C43C-0236    [Abstracts]
TI: Automatic, Satellite-Linked "Webcams" as a Tool in Ice-Shelf and Iceberg Research.
AU: * Ross, R
EM: rr@thistle.org
AF: Stanford University, 420 Linden St., San Francisco, CA 94102 United States
AU: Okal, M H
EM: mho@midway.uchicago.edu
AF: University of Chicago, Department of the Geophysical Sciences 5734 S. Ellis Ave., Chicago, IL 60637 United States
AU: Thom, J E
EM: jthom@ssec.wisc.edu
AF: University of Wisconsin-Madison, Space Science and Engineering Center 1225 W. Dayton St., Madison, WI 53706 United States
AU: MacAyeal, D R
EM: drm7@midway.uchicago.edu
AF: University of Chicago, Department of the Geophysical Sciences 5734 S. Ellis Ave., Chicago, IL 60637 United States
AB: Important dynamic events governing the behavior of ice shelves and icebergs are episodic in time and small in scale, making them difficult to observe. Traditional satellite imagery is acquired on a rigid schedule with coarse spatial resolution and this means that collisions between icebergs or the processes which create ice "m‚lange" that fills detachment rifts leading to ice-shelf calving, to give examples, cannot be readily observed. To overcome the temporal and spatial gaps in traditional remote sensing, we have deployed cameras at locations in Antarctica where research is conducted on the calving and subsequent evolution of icebergs. One camera is located at the edge of iceberg C16 in the Ross Sea, and is positioned to capture visual imagery of collisions between C16 and neighboring B15A. The second camera is located within the anticipated detachment rift of a "nascent" iceberg on the Ross Ice Shelf. The second camera is positioned to capture visual imagery of the rift's propagation and the in-fill of ice m‚lange, which constrains the mechanical influence of such rifts on the surrounding ice shelf. Both cameras are designed for connection to the internet (hence are referred to as "webcams") and possess variable image qualities and image-control technology. The cameras are also connected to data servers via the Iridium satellite telephone network and produce a daily image that is transmitted to the internet through the Iridium connection. Results of the initial trial deployments will be presented as a means of assessing both the techniques involved and the value of the scientific information acquired by these webcams. In the case of the iceberg webcam, several collisions between B15A and C16 were monitored over the period between January, 2003 and December, 2004. The time-lapse imagery obtained through this period showed giant "push mounds" of damaged firn on the edge and surface of the icebergs within the zones of contact as a consequence of the collisions. The push mounds were subsequently unstable, and calved as small scale ice debris soon after the collision, thereby returning the iceberg edge to a clean, vertical cliff-like appearance. A correlation between the iceberg collision record available from the webcam and data from a seismometer located on C16 is anticipated once the seismometer data is recovered. The webcam associated with the detachment rift of the nascent iceberg on the Ross Ice Shelf is planned to be deployed in early November, 2004. If results are available from this deployment, they too will be discussed.
DE: 9310 Antarctica
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1894 Instruments and techniques
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting