Author:
BIGGS NICHOLAS R. T.,MORALES MAQUEDA MIGUEL A.,WILLMOTT ANDREW J.
Abstract
Previous polynya flux models have specified a constant value for the collection
thickness of frazil ice, H, at the polynya edge. In certain circumstances, this approach
can cause the frazil ice depth, h, within the polynya, to exceed H, a result which
violates assumptions made in the formulation of the ice flux balance equations at
the polynya edge. To overcome this problem, a parameterization for H is derived
in terms of the depth of frazil ice arriving at the polynya edge and the component,
normal to the polynya edge, of the frazil ice velocity relative to the velocity of the
consolidated ice pack. Thus, H is coupled to the unknown polynya edge. Using the
new parameterization for H, an analysis of the unsteady one-dimensional opening
of a coastal polynya is presented. Analytical solutions are also derived, using the
new parameterization for H, for steady-state two-dimensional polynyas adjacent to a
semi-infinite and finite-length coastal barrier, the latter case representing a prototype
island. In all cases, the solutions show close qualitative and quantitative agreement
with those derived using a constant value for H. However, the steady-state two-dimensional polynya edge can, in certain circumstances, exhibit a corner at the point
where the offshore equilibrium width is reached. Precise conditions for the existence
of a corner are derived in terms of the orientation of the frazil ice velocity (u) and
the consolidated ice velocity (U). Upper and lower bounds are also obtained for the
area of the steady-state island polynya, and it is shown that over a large range of
orientations of u and U, the area exceeds that associated with the island polynya
with constant H. Finally, two simulations of the St. Lawrence Island Polynya are
presented using the new parameterization for H, and the results are compared with
the H-constant theory.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
38 articles.
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