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|Title:||Sea ice drag laws and simple boundary layer concepts, including application to rapid melting|
|Authors:||United States. Office of Naval Research.|
McPhee, Miles G.
|Keywords:||Boundary layer flow|
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||CRREL report ; 82-4.|
Abstract: Several proposed methods for treating the momentum flux between drifting sea ice and the underlying ocean are interpreted in terms of simple planetary-boundary-layer (PBL) turbulence theory. The classical two-layer approach, in which the solution for a thin surface layer is matched to an Ekman solution for the outer layer, is used to derive several forms for the drag law. These forms range from linear (where stress is proportional to relative speed), through quadratic (where stress is proportional to relative. speed squared), to a Rossby-similarity law like that used to express frictional drag on geostrophic wind in the atmosphere. Only formulations which conform with Rossby-similarity scaling are consistent with free-drift data from the 1975 AIDJEX drift station experiment. We show how a two-layer model, in which the nondimensional stress is allowed to vary realistically through a surface layer of constant nondimensional thickness, provides an analytic solution for the steady-state PBL equation quite similar to recent numerical solutions. The theory is extended to include drag reduction due to buoyancy from rapid melting and is shown to agree with atmospheric results for geostrophic drag under analogous conditions of radiational cooling. The theory provides a basis for estimating trajectories and melt rates of floes drifting into water warmer than the ice melting temperature.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||CRREL Report|
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