Accession Number : ADA181392

Title :   Investigation of Ice Dynamics in the Marginal Ice Zone.

Descriptive Note : Final technical rept. Jan 83-Apr 86,

Corporate Author : MARINE RESEARCH INST HELSINKI (FINLAND)

Personal Author(s) : Leppaeranta,Matti ; Hibler,William D. , III

Report Date : 23 APR 1987

Pagination or Media Count : 116

Abstract : The dynamics of sea ice in the marginal ice zone (MIZ) are considered both from theoretical and from experimental point of view. Ice kinematics measurements were made with the Del Norte microwave trisponder system in MIZEX-83 and MIZEX-84 Greenland Sea experiments. Differential ice motion was measured with four to six stations on the ice in the scale of 2-20 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 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. Analysis of current measurements beneath the drifting ice show that current variations show up highly damped in the ice. In differential motion, ice-current coherence was significant only at low frequencies (lower than one cycle per day).

Descriptors :   *SEA ICE, *RHEOLOGY, CYCLES, DRIFT, DYNAMICS, FREQUENCY, ICE, INERTIAL SYSTEMS, KINEMATICS, LOW FREQUENCY, MEASUREMENT, MOTION, NOISE, PEAK VALUES, RATES, RED(COLOR), SHEAR PROPERTIES, STATIONS, VARIATIONS, VELOCITY, GREENLAND SEA, VISCOPLASTIC PROPERTIES, DEFORMATION, THICKNESS, PACK ICE, MATHEMATICAL MODELS, EDGES, SEA WATER, WATER WAVES, INTERFACES, OCEAN CURRENTS, FINLAND

Subject Categories : Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE