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Modeling macro-porosity of ridged sea ice in basin-scale models

Presented by: 
Andrew Roberts Naval Postgraduate School
Wednesday 13th September 2017 - 09:45 to 10:30
INI Seminar Room 1
Co-authors: Elizabeth Hunke (Los Alamos National Laboratory), William Lipscomb (National Center for Atmospheric Research), Samy Kamal (Naval Postgraduate School), Wieslaw Maslowski (Naval Postgraduate School)

One of the largest limitations of current-generation sea ice models is that they characterize sea ice morphology using a thickness distribution, g(h), over an area A(x). This inherently introduces a scale limitation to sea ice models, because g(h) only represents the relative quantity of ice of thickness, h, over a region, rather than describe how thickness is locally organized. Moreover, the approach assumes that sea ice deformed into rafts, folds, buckles, ridges and hummocks is equally as porous as undeformed ice, despite strong evidence to the contrary. This problem may be addressed by expanding the state space of the thickness distribution to become a multivariate distribution g(h,phi) where phi is the macro-porosity of sea ice rubble. Then, sea ice ridging may be described using a Euler-Lagrange equation for ridge cross-sections that mimic many of the characteristics of existing ridge-scale simulations. The approach requires careful consideration of non-conservative components of ridging, and, in the most basic approach, can use a Coulombic failure criteria applied vertically within ridges to predict their angle of repose, macro-porosity, extent and seperation in large scale models. This talk presents the theoretical basis for this new method of simulating sea ice thickness.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons