Improved sea ice parcel trajectories in the Arctic via data assimilation

An assimilated sea ice motion product is used to track ice parcels in sever al regions of the Arctic over time periods of one day to several weeks duri ng 1992-1993, Motions simulated using a two-dimensional, dynamic-thermodyna mic sea ice model are combined with motions derived from daily 85 GHz speci al sensor microwave/imager (SSM/I) imagery using an optimal interpolation m ethod that minimizes error covariance, Assimilation attenuates the tracking error over the stand-alone model in comparison to buoy trajectories with t he same starting location and time. The average 14-day assimilated trajecto ry's displacement error is as much as 34% lower than the model trajectory, while the RMS direction error is decreased by up to 10 degrees (24%). Assim ilation can also yield an estimate of dispersion, which is not retrievable by point buoy observations. An assimilation approach improves estimates of ice drift and has the potential to further the understanding of ice mass fl ux, freshwater flux, and pollutant transport in the polar regions. (C) 2001 Elsevier Science Ltd. All rights reserved.