Subsynoptic scale spatial variability of sea ice deformation in the western Weddell Sea during early summer

Ice Station Polarstern (ISPOL), deployed in the western Weddell Sea from November 2004 to January 2005, included a study of subsynoptic scale variability in sea ice velocity and deformation using an array of 24 buoys. Upon deployment, the ISPOL buoy array measured 70 km in both zonal and meridional extent and consisted of subarrays that resolved sea ice deformation on scales from 10 to 70 km. Across the ISPOL array, divergence varied and did not show a distinct coherent length scale. Spectral analysis of divergence and shear of subarrays revealed that deformation did not vary smoothly across the array. This indicates variability of internal ice stress on the scale of 10 km. Ice conditions within the ISPOL array encompassed two distinct regimes separated by shear along the continental shelf break. Differences in spectral power of the tidal and inertial bands across the two regions do not mirror expected differences due to spatial variability of tide-induced deformation on the shelf break. Instead, they indicate that the pack ice's internal stress behaved anisotropically on the scale of the shear zone (across the buoy array, 70 km).