Characterizing the marginal ice zone in the Greenland Sea through seasonal floe-scale sea ice observations

Sea ice motion in the marginal ice zone (MIZ) is inherently multi-scale, influenced by the relationship between the floe size distribution (FSD) and the temporal and spatial scales of winds and ocean currents. Joint observations of the FSD and motion are necessary to develop and validate models of the MIZ. However, such observations are rare. We present observations of floe-scale Lagrangian sea ice translation and rotation in the East Greenland MIZ spanning the spring-to-summer transition for years 2003-20. The observations are derived from moderate-resolution optical imagery using the Ice Floe Tracker (IFT) algorithm and consist of floe shapes, geometric properties, and trajectories. We investigate FSD seasonality, links between floe size, translation, and rotation, and length scale dependence of horizontal deformation. The FSD evolves from April to July, with increasing prevalence of small floes. Variability of both drift speed and rotation depend on the floe size. Deformation rates show strong length scale dependence and vary seasonally. Comparisons to large-scale sea ice motion and to discrete element model simulations show that deviations from the mean drift resolved by IFT are exponentially distributed, suggesting ocean turbulence is resolved. These observations provide new information for sea ice model development and validation in the MIZ.