Assimilation of observed ice motions in a 2-D sea ice model

Assimilation of observed daily ice motions have been shown to significantly improve model ice motion estimates by reducing bias, RMS error, and improving correlation with buoys. Additionally, assimilation can add spatial variability that is missed by low-resolution models forced by low-resolution wind and current fields. However, the assimilated ice motions may not lead to realistic changes in ice thickness or area. One possible reason is that the observed ice motions, computed once per day from satellite imagery and buoy displacements, may miss important sub-daily inertial motions of the sea ice. Sub-daily oscillation of sea ice motion can potentially have a significant effect on the evolution of the model ice thickness and ice area fields. In this study, sub-daily variability is added to the observed daily motion estimates to investigate the effects on model ice thickness and ice area.