AIDJEX Bulletin #40 - Polar Science Center - University of Washington

fc is the Coriolis parameter,
- k is a unit vector normal to the earth's surface;
To study the quasi-steady problem, we should not neglect mg, but instead
write:
where & = ag/ag is the velocity gradient. The model is then written in an
Eulerian description.
Now it is meaningful to neglect av_/at so that time
dependence may be ignored. With these assumptions in mind, we may write the
Cartesian components of momentum balance as
where Cartesian components of all tensors are introduced:
and the water stress law may include any nonlinear algebraic response that
depends only on the ice velocity relative to geostrophic ocean currents
(McPhee, 1975).
The constitutive law used to simulate sea ice dynamics is elasticplastic
(Coon et al., 1974; Coon and Pritchard, 1974; Pritchard, 1975).
However, the elastic response is included primarily to help obtain a numerical
solution. A rigid-plastic material law is thought to be as reasonable
from a physical standpoint. Our analysis of characteristics to date has
treated only the rigid-plastic model. Therefore, we must exercise care when
the results of this analysis are used to interpret possible discontinuities
in numerically calculated results. But we shall study the mathematical
properties of the rigid-plastic model, and from these results we expect to
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