Scaling aspects of the sea-ice-drift dynamics and pack fracture

摘要

A study of the sea-ice dynamics in the periods of time prior to andduring the cycles of basin-wide fragmentation of the ice cover in the ArcticOcean is presented. The fractal geometry of the ice-sheets limited by leadsand ridges was assessed using the satellite images, while the data on thecorrelated sea-ice motion were obtained in the research stations "NorthPole 32" and "North Pole 33" established on the ice pack. The revealeddecrease of the fractal dimension as a result of large-scale fragmentationis consistent with the localization of the fracture process (leadspropagation). At the same time, the scaling properties of the distributionof amplitudes of ice-fields accelerations were insensitive to the event ofsea-ice fragmentation. The temporal distribution of the accelerations wasscale-invariant during "quiet" periods of sea-ice drift but disordered inthe period of mechanical perturbation. The period of decorrelated (in time)ice-field motion during the important fracture event was interpreted as aninter-level transition in the hierarchic dynamical system. The mechanism ofthe long-range correlations in the sea-ice cover, including the fractureprocess, is suggested to be in relation with the self-organized oscillationdynamics inherent in the ice pack.