Accession Number : ADA138558

Title :   Investigation of Ice Dynamics in the Marginal Zone.

Descriptive Note : Final technical rept. Jan-Dec 83,

Corporate Author : MARINE RESEARCH INST HELSINKI (FINLAND)

Personal Author(s) : Leppaeranta,M ; Hibler,W D , III

PDF Url : ADA138558

Report Date : Dec 1983

Pagination or Media Count : 106

Abstract : Modeling studies were carried through with three types of ice rheologies: free drift, linear viscosity, and plasticity. It is suggested that ice thickness variations may be important to the dispersion of ice edge and lead to e.g. clustering of ice floes. Analytic linear viscous solutions show that variable ice strength rather than variable forcing is likely to produce sharp changes in ice velocity near the ice edge. Steady state ideal plastic solutions give a constant ice flow under constant forcing in the MIZ. In general, ice interaction has a rectifying effect on the flow pattern. Ice kinematics measurements were made with the Del Norte microwave trisponder system in MIZEX-83 Greenland Sea experiment. Differential ice motion was measured with four stations on the ice in the scale of 5 km at three-minute intervals. On several occasions, a rapid slip occurred in measured distances. Ice velocity fluctuations were typically of the order of 1 cm/s and large deformation rates a few per cent per hour. Various spectra of differential ice drift showed a moderate inertial peak and a red noise character at higher frequencies, up to about half-hour period. The maximum rate of shear was about twice as large as divergence from 12-h to about 2-h period.

Descriptors :   *Sea ice, Greenland sea, Arctic regions, Offshore, Dynamics, Rheology, Drift, Viscosity, Plastic properties

Subject Categories : Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE