Small-scale sea ice deformation during N-ICE2015: From compact pack ice to marginal ice zone

摘要

We studied small-scale (50 m to 5 km) sea ice deformation from ship radar images recorded during the N-ICE2015 campaign. The campaign consisted of four consecutive drifting ice stations (Floes 1-4) north of Svalbard, with a total duration of nearly 5 months. Deformation was calculated using 5 different time intervals from 10 min to 24 h, and the deformation rate was found to depend strongly on the time scale. Floes 1-3 had a mean deformation rate within the range of 0.06-0.07 h~(-1) with the interval of 10 min, and 0.03-0.04 h~(-1) with the interval of 1 h. Floe 4 represented marginal ice zone (MIZ) with very high deformation rate, 0.14/0.08 h~(-1) with the interval of 10 min/1 h. Deep in the ice pack, high deformation rates occurred only with high wind and drift speed, while in MIZ they were found also during calm conditions. The deformation rates were found to follow power law scaling with respect to length and time scale even on this small scale and in small domain (15 km × 15 km). The length scale dependence of deformation rate depends on the time scale: the power law scaling exponent β of the whole study period decreases from 0.82 to 0.52 with the time interval increasing from 10 min to 24 h. Ship radar images reveal the importance of the deformation history of the ice pack, since the deformation events were initialized along the lines of previous damages.