HR: 0800h
AN: C11B-0458    [Abstracts]
TI: Theoretical Impact of the Inverse Barometer Effect on Giant Icebergs of the Ancient Arctic
AU: * Turnbull, I D
EM: iant@uchicago.edu
AB: Erosional plowmarks or flutes (furrows) 700 to 1000 m below the sea surface on the floor of the Lomonosov and Northwind Ridges, and the Chukchi Borderland and Yermak Plateau in the Arctic Ocean provide convincing evidence that icebergs carved this region over a period of time ranging from 600 to 20 kybp. [Reed, 2001], [Polyak et al., 2001], and [Kristoffersen et al., 2004] However, taking into account the fact that sea level was lower by 100 to 150 m during glacial periods than during interglacials, and that modern icebergs calving off Greenland and Antarctica are never more than 550 m thick, leads us to the conclusion that these ancient icebergs must have been about 800 to 900 m thick to be able to reach the sea floor. [Reed, 2001] and [Kristoffersen et al., 2004] Here, I evaluate the effect the IBE may have had on an iceberg with the horizontal dimensions of the Antarctic iceberg B15A through experimentation in my theoretical model. In comparison to experiments involving modern iceberg drift, an adjustment I needed to make in the model configuration besides increasing the iceberg thickness to 800 m was to replace ocean current drag across the bottom surface with the basal friction force of ice sliding on till sediment of the ocean floor. I also assume that the sea surface gradient gravitational force should have no impact on grounded icebergs, so in reality I am only testing the impact of the pressure gradient force in determining the theoretical trajectories of the ancient mega-bergs. I also assume that the iceberg is barely grounded or buoyant, so that the freeboard is still approximately \frac{1}{10^th} of the iceberg's total height.
DE: 0732 Icebergs
SC: Cryosphere [C]
MN: 2007 Fall Meeting