Sub-daily sea ice motion and deformation from RADARSAT observations

We find a persistent level of oscillatory sea ice motion and deformation, superimposed on the large-scale wind-driven field, in May 2002 (spring) and February 2003 (midwinter), in the high Arctic over a region centered at similar to(85degreesN, 135degreesW). At this latitude, the RADARSAT wide-swath SAR coverage provides 4-5 sequential observations every day, for ice motion retrieval, with a sampling interval at the orbital period of similar to101 minutes. Periodic correlations in ice motion and deformation can be seen in length scales from 10 km and above, and suggest a 12-hr oscillation that is more likely associated with inertial rather than tidal frequencies. Divergence/convergence of similar to0.1-0.2% peak-to-peak or rates of similar to10(-7)/s is seen in both datasets, with the mid-winter dataset having smaller values. These observations are remarkable in that short-period ice motion is previously believed to be inhibited by the strength of the ice pack in the high Arctic during winter. New ice production due to the recurrent openings and closings at these temporal scales, if ubiquitous, could be significant within the winter pack.